My connections (mentioned a wee bit down the post list) in Rathven Parish are local to Buckie. My G-G-Grandmother was born in Buckie in 1863.She had an elder brother Alexander, born 1853 in Portessie, which is on a three-mile stretch of shoreline spitting distance east of Buckie.
His birthdate is listed as 1853, but I don't think he's who you are looking for, since the only spouse I have for him is Jane Cormack. I have six children listed for him:
Williamb. 1878 in Lossiemouth Isabellab.? Janeb. 1881 in Lossiemouth Barbarab. 1883 in Lossiemouth Alexanderb. 1893 in Lossiemouth Robert George c. 1893 in Lossiemouth
Still, considering how small the area is I'm sure there must be a connection there. If you're having trouble finding information for people in Buckie it could be because they relocated to Lossiemouth -- according to an obituary of my G-G-Grandfather, "Mr. Campbell . . . was a native of Portessie, and one of the first of the fishermen who came from the Banffshire coast and settled in Lossiemouth about 46 years ago."(The Elgin Courant, 1910) Apparently the fishing went bad and many of the Buckie families relocated to nearby Lossiemouth.
Anyway, I'd like to hear more detail from you, and to pass on some more information I have on Cormacks in Banffshire and Rathven. If you're interested please contact me.