The index to Bath Co. probate records lists Robert Riddle in Bk. 1, pp. 334, 392-393. I have not looked at the records.

Some data on this family from correspondence with Maxine Johnson.

1840 census of Bath Co, KY, lists:
1 male 20-29 yrs, 1 female 20-29 yrs,1 male 5-9 yrs, 3 males 0-4 yrs.

1850 census of Bath Co., KY, lists:
Robert Riddle, 39; Lucinda, 37; James W., 14; Andrew H., 13; William L., 12; George A., 10; Catharine E., 7; Mary C., 6; Nancy, 5; Alzianda, 3; Sarah, 11/12. All born in Kentucky.

The 1860 census of Bath Co., Ky, Owingsville, seems to list the widow Lucinda Riddle twice, with a slightly different list of children, but sufficiently similar that it is clearly the same family. My guess is that Harrison had established a household of his own, and sometimes his mother and siblings lived with him.

First is family #1066 on page 149 (enumerated 27 July):
Lucinda Riddle, 47; George, 20; Catherine, 19; William, 22; Mary, 17; Ann, 14; Sarah, 11; Matilda, 9; Zachariah, 7; James M., 1. All born in Kentucky. (I don't know who is the father of James M. Probably he is a grandson of Lucinda & Robert, but by which child?)

And 99 families later, in family #1165 on pp. 162-163 (enumerated 31 July):
Lucinda Riddle, 48; Harrison, 23; William, 21; George, 20; Catharine, 19; Nancy, 17; Caroline, 16; Mahala, 14; Sarah, 12; Matilda, 10. All born in Kentucky.

1870 census of Fleming Co., Ky, Hillsboro precinct, enumerated 2 Aug, lists on p. 11 as family #71/69:
Riddell, Lucinda, 59, farmer; William, 32, farm laborer, idiotic; Matilda, 19; George, 31; Catharine, 29; Sarah, 21. All born in Kentucky.
(This census does not record relationships or marital status.)