A number of details are usually needed:
- Is this the only copy or did you make the copy from one in a public repository? If it comes from a personal copy of the original rather than from a repository, you document that and that you are the repository.
- If it was in a public repository, you would cite where you got it. A photocopy in your possession isn't really important but could be mentioned.
A normal land record citation provides:
Item of interest, record date, series it came from, record group, repository info.
A detailed citation depends on a number of factors so if you provide all the details you recorded when you made the photocopy, a source citation can be constructed.