I have in my family tree a Robert Annan (or Anman) Rankin who lived in Maury County by the late 1820's and is said to have moved to Mississippi by 1838. I don't have any information on his wife. His father was the Rev. Adam Rankin of Lexington, Kentucy (which is where Robert was born). His mother died in Columbia and is buriedn in the Greenwood(?) Cemetery. Her name was Martha McPheeters Rankin, and she died on July 27, 1836.
You believe the Robert you mentioned may have married a McKee?