Inclusion Criteria:  1. Individuals who are willing to participate in the study and comply with its procedures.  2. Individuals who are able to give written informed consent. 3. Individuals between 18-70 years old. 4. Has a BMI between 18-32 kg/m2 (inclusive). 5. Individuals who are willing to not undertake overseas travel for the duration of the study or engage in excessive sun-exposure or use of sun lamps or tanning beds for the duration of the study.  6. Individuals who are willing to maintain their current diet and not change supplement usage for the duration of the study.  7. Individuals who are willing to self-administer finger prick sampling. 8. Individuals who are willing to avoid strenuous exercise or exposing the patch to external sources of direct heat e.g., heating pads or electric blankets, heat lamps, saunas, hot tubs, heated water beds, and prolonged direct sunlight, while wearing the patch.  9. Individuals willing to refrain from swimming or other sports involving immersion in water for the duration of the study.  10. Individuals who have Serum 25-Hydroxyvitamin D concentration of ≥15 nmol/L and ≤100 nmol/L at screening.  Exclusion Criteria:  1. Are less than 18 or greater than 70 years old. 2. Participants who are pregnant, breastfeeding, or wish to become pregnant during the study.  3. Individuals currently of childbearing potential, but not using an effective method of contraception, as outlined below:  Complete abstinence from intercourse two weeks prior to administration of Investigational Product, throughout the clinical trial, until the completion of follow-up procedures or for two weeks following discontinuation of the Investigational Product in cases where participant discontinues the study prematurely. (Participants utilising this method must agree to use an alternate method of contraception if they should become sexually active and will be queried on whether they have been abstinent in the preceding 2 weeks when they present to the clinic for the Final Visit). Has a male sexual partner who is surgically sterilised prior to the Screening Visit and is the only male sexual partner for that participant. Sexual partner(s) is/are exclusively female. Use of acceptable method of contraception, such as a spermicide, mechanical barrier (e.g., male condom, female diaphragm) or contraceptive pill. The participant must be using this method for at least 2 weeks prior to use of the Investigational Product and at least 1 week following the end of the study.  Use of any non-hormonal intrauterine device (IUD) or contraceptive implant with published data showing that the highest expected failure rate is less than 1 % per year. The participant must have the device inserted at least 2 weeks prior to the first Screening Visit, throughout the study, and 2 weeks following the end of the study.  4. Individuals who are hypersensitive to any of the components of the investigational product.  5. Individuals who have a condition affecting the integrity of the skin (e.g., psoriasis or eczema).  6. Individuals who are taking, or have taken, any prescribed or over the counter (OTC) drug and antacids, supplements, or herbal remedies in the 14 days before patch administration including any drugs known to interfere with vitamin D metabolism (e.g., steroids, orlistat, cholestyramine, phenytoin, statins, thiazide diuretics etc.). Occasional use of paracetamol up to a maximum of 2 g per day, hormone replacement therapy [HRT] or hormonal contraception are permissible.  7. Individuals who have taken calcium supplements within the previous 8 weeks. 8. Individuals who are taking vitamin D supplements greater than 10 micrograms per day.  9. Individuals with any history of or concurrent clinically significant diseases or conditions (e.g., kidney or liver dysfunction).  10. Individuals with a known history of allergy to plasters or patches. 11. Individuals who have planned major changes in lifestyle (i.e., diet, dieting, exercise level, travelling) during the duration of the study