Yes, another problem is naming patterns, since there are a lot of Johns and Peters in different branches. Frustrating. However, one candidate I have for John's parents are Thomas and Sally (Findley) Rickman in Patrick Co., VA. They were married on 23 December 1806 and are listed in the 1830 census with a free colored male under 10, who could be John. Also, in November 1829, John Rickman, son of Thomas Rickman, was registered as a free Negro by the clerk of Patrick Co. court (I found all of this on the web).
Wish I could be of more help. You could also post on the Free Persons of Color forum on AfriGeneas (www.afrigeneas.com/forum-fpoc/index.cgi/), where several people are working on Rickmans, particularly the Indian connection. -- Gordon