An Open-label Study That Will Test a Second Treatment Session of RZL-012.

Inclusion Criteria: For a subject to be eligible for this study, he or she must meet all of the following criteria: 1. Is a male or female subject between the ages of 18 and 65 years, inclusive. 2. Previously treated with RZL-012 under protocols RZL-012-SMF-SWMTG-P2US-001 or RZL-012-SMFC-P2US-001 and whose current C-CAT score is 2, 3 or 4 3. Who successfully completed (as in completed the day 84 visit) the RZL-012-SMF-SWMTG-P2US-001 or RZL-012-SMFC-P2US-001 studies. 4. Has body mass index (BMI) between \>22 kg/m2 and \<40 kg/m2. 5. Has SMF bulge that is contiguous and can receive between 16 to 36 injections distanced 1 centimeter (cm) from each other according to the injection grid. 6. Has stable weight, with no fluctuation of \>5 kg in the past 12 months. 7. If female, is not pregnant or breastfeeding based on the following: 1. agree to the use of highly effective contraceptive methods for at least 2 weeks before baseline until 4 weeks after the last day of study drug and a negative serum pregnancy test (ß-hCG) at screening and negative urine pregnancy test at baseline; or 2. is abstaining 3. is of nonchildbearing potential defined as clinically infertile as the result of surgical sterilization (hysterectomy, bilateral tubal ligation, and/or bilateral oophorectomy); or 4. is confirmed postmenopausal status (defined as either having amenorrhea for ≥ 12 consecutive months without another cause or documented serum follicle-stimulating hormone (FSH) level \> 40 mIU/mL or another documented medical condition (e.g., was born without a uterus)) NOTE: The following are considered highly effective contraceptive methods: hormonal oral contraceptives, injectables, and patches; intrauterine devices; double-barrier methods (synthetic condom, diaphragm, or cervical cap used with spermicidal foam, cream, or gel); and male partner sterilization. 8. If male (with or without vasectomy), agree to the use of highly effective contraceptive methods as listed above in criteria 7 as well as to use a barrier method, e.g. condom, from study check-in until 7 days after drug injection. 9. Is willing to avoid strenuous exercise for seven (7) days post treatment. 10. Can adhere to the visit schedule and protocol requirements and be available to complete the study. 11. Is willing and able to sign an Institutional Review Board (IRB) approved informed consent form (ICF) indicating that they are aware of the investigational nature of the study. Exclusion Criteria: * Subjects must NOT meet any of the following Exclusion criteria to be eligible for enrollment: 1. Is unable to tolerate subcutaneous injections. 2. Any subject who had any treatment related SAE's or allergic reactions to treatment in the previous RZL-012 studies. 3. Has any systemic disease including but not limited to gastritis or ulcers, renal dysfunction, hypertension, liver disease, glaucoma, diabetes and/or cardiovascular disease, regardless of whether the condition is controlled with medication. 4. Has skin laxity (i.e., elastosis, skin crepiness, skin redundancy, skin draping, vertical and/or horizontal skin bands and folds, blunting of cervical mental angle, loss of opposition of skin to underlying neck structures due to skin laxity) that could obscure the evaluation and treatment of SMF. 5. Has any scars, unshaven hair, tattoos, facial hair, or jewelry on or near the proposed treatment area. 6. Has presence of structures or confounding factors that may interfere with assessing SMF such as but not limited to enlarged submandibular salivary and/or parotid glands, micrognathia, chin implant, soft tissue volume augmentation of chin and/or jawline, pronounced platysmal bands and deep necklace lines or presence of facial jowls that could obscure the evaluation of SMF. 7. Has a fat bulge under the chin that is too large to be adequately treated by 36 contiguous injections on a 1cm grid . 8. Has a fat bulge under the chin that is of an insufficient volume to allow 16 injections within a contiguous 1 cm grid. 9. Has significant history or current evidence of a medical, psychological, or other disorder that, in the Investigator's opinion, would preclude enrollment in the study. 10. Has an active bacterial, fungal, or viral infection in the proposed treatment area. 11. Has a pre-existing skin condition in the submental region that, at the Investigator's discretion, may confound evaluation or analysis. 12. Has previously had treatments or surgery in the submentum, such as but not limited to, focused ultrasound, radiofrequency, cryolipolysis, liposuction, sodium deoxycholate, or neck lift. 13. Has pre-existing neurological or gastrointestinal condition leading to dysphagia, dysphonia, or facial nerve palsy. 14. Has Dercum's Disease. 15. Has allergic reactions to injectables 16. Has any pre-existing medical condition other than increased SMF that, at the Investigator's discretion, may result in increased submental fullness, such as but not limited to, thyroid enlargement, goiter, cervical lymphadenopathy, etc. 17. Has a planned fat reduction procedure of any variety to the submental region for the duration of the study. 18. Has medication or a history of coagulopathy. 19. Has a history or family history of venous thrombotic disease. 20. Has been treated chronically at least three (3) months prior to study entry with systemic steroids or immunosuppressive drugs. 21. Has been treated chronically at least one (1) week prior to study entry with non-steroidal anti-inflammatory drugs (NSAIDs) 22. Has used anticoagulation therapies that may increase bleeding or bruising (i.e., aspirin, ibuprofen/Celecoxib, warfarin, vitamins, and herbal preparations) for seven (7) days prior to treatment. 23. Has had treatment with botulinum toxin injections in the neck or chin area within nine (9) months prior to screening. 24. Current participation or participation within three (3) months prior to the start of this study in a drug or other investigational research study.