Both the forsaker and the foe hunter prestige classes
have stackable spell resistance. Does this stack with spell
resistance from a magic item? What about racial spell
resistance? Suppose I have a drow ranger 7/foe hunter 4.
Is his SR equal to 41 (22 racial + 19 foe hunter; assuming
that the +1/level racial bonus also stacks with the +1/level
foe hunter bonus)? What happens if I add magic armor
that grants SR 11? Is my SR now 52?
   A foe hunter or forsaker's SR stacks with SR from most
other sources; however, don't count a character level twice
when calculating the character's total SR, and don't stack two
SRs with each other, only with the prestige class bonus. If
you have two or more SRs that don't stack, use the best
combination.
   The sample character has the following:
   Foe hunter SR 19 (base 15 + 4 for foe hunter levels);
   Armor SR 11;
   Drow SR 22 (base 11 + 11 class levels);
   Add the armor to the foe hunter;
   (SR 30).
   Do not add the drow SR because it already takes level into
account, and in any case, you wouldn't stack armor SR and
drow SR because those two SRs don't stack. Note that in this
case, the SR of 30 applies only against effects that come from
a hated enemy. Magic from other sources has to overcome
the character's drow SR of 22.