This is confusing me. Say I have a racial spell resistance, 12 + class levels, and the Foe Hunter spell resistance, 15 + Foe Hunter Levels, and say I am level 10. According to the actual printing of the class they explicitly stack. According to the FAQ, any class levels are only counted once. So would my SR be 12 (racial) + 10 (classes) + 15 (Foe Hunter) + 4 (Foe Hunter class levels)? Or am I doing something wrong?
In your calculation, you are counting you Foe Hunter levels twice. A FAQ-ruling of the SR can be calculated two ways. For this purpose I will assume the character is 10th level: Ranger 6/Foe Hunter 4.
Racial SR of 12+class levels (not counting foe hunter class levels) + 15+foe hunter levels.
12+6 + 15+4 = 37 versus your hated foe.
12+6+4 = 22 vs all others.
This is clunky and confusing.
A better way to do it is to just do SR of 12+ class levels +15. This accounts for your foe hunter levels once (along with all your other levels), and makes it easy to see your SR vs things that are not your hated foe.
12+10+15 = 37 vs hated foes
12+10 = 22 vs all others
This is of course assuming you want to follow the suggestion of the FAQ, to only have each class level counted once.