However, locating the individual should not be too difficult as the front does provide clues.
The Reed woman was aged 72 in 1884, making her born in approximately 1812 (she's a woman because she is referred to as "she" in the statement). Reed was living in Mercer County, Kentucky, in 1830 when the Greens were married. Most likely this unnamed Green woman lived in Mercer County from 1830 until the time this statement was made out. Probably, but there is no guarantee she didn't live in a different state for forty years only to return to Kentucky in the 1880s. Despite this possibility, attempts to locate the Green woman should begin with the 1880 census and work backwards.
Without knowing when this lady was married, it is possible that she is enumerated in the census under a different last name. Most likely she has the same surname in 1880 that she had in 1884. Locating her in pre-1850 census records will be difficult because those enumerations only list heads of household.
A Henry S. Reed is a witness to Reed's signature. It is possible that he is either her husband or her son.
Why do I care who this person is?
I care because this person was at the wedding of Thomas and Sarah Brown in 1830 and was someone with whom they had not lost touch 54 years later. That hints at a potential relationship between the Reed witness and one of the Browns.
I just hate it when holes are in the most inappropriate place in a document.
We'll have an update when there's information to warrant one.