Per Alyce-James flintlock from Kit R. and the matchlock that I just picked up, we can confirm that Kit’s maker’s mark to be an offset ‘R’ to the right and on top of a ‘K’.
In addition, he serialized all his arms in a 3 to 4 digit numeric, where the 1st one or two numbers were the build number of the year and the last two signify the build year. So a ‘2085’ would be his 20th gun from 1985.