Different branch. Your line descends via Raleigh Harwell Abernathy (1778-1858), grandson of John Abernethy Sr (1723-1819) of VA. The branch Dr. Smith concentrated on was that of James Abernethy (1790-1859) of NC. He was a son of Charles Abernethy (1748-1824) & wife Barbara Ellis Cobb. Dr. Smith's work is available on two different LDS microfilms: 926199 item 5 and 1213612 item 3.
Caution: there are mistakes even in his work, as thorough and estimable as it was.