The citation is roughly the same whether you found it in an on-line repository like Family Search or you have obtained a hard copy for your personal use.
The citation should name the agency that has the original document or record, e.g. "Commonwealth of Virginia Department of Health," the birth certificate no., the person's name, date, location, if it's a certified copy and the date it was issued, then that it's in the possession of [your Wiki Id and name]. You can also transcribe any other information that's on the certificate, such as parents' names, ages, place of birth, etc. This is especially helpful if the birth certificate isn't on-line or easily viewable.
