The only record of this marriage that I am aware of (having searched the family for 30+ years) is from their Bible record published by the WV DAR 1965-1968 "Your Ancestors and Mine, WV Bible Records," page 8. No location for the marriage is given.
Allegany County, MD, Deed Book B:35-37, dated 4 February 1795, states that he is "of Allegany County in the state of Maryland. . . ." This is the closest to his marriage date that I can document his residency, and presumably since he was purchasing land on this date he still resided in Allegany County 2 months later when he married. Thus, the best we can do for a location of this marriage is "probably Allegany County, MD."
BTW, Elizabeth, wife of Mark Brayfield, was his second (or perhaps later) wife and not the mother of Amelia.