Normally with potions you are the caster and target, thus SR would not apply. But if you are force fed a potion is this still the case or would SR still deny the spell?
Spell resistance doesn't interfere with a potion's effect
Spell Resistance says that it "never interferes with [a creature's] own spells, items, or abilities."
"Potions are like spells cast upon the imbiber," says Potions on Price of Potions, but "[t]he drinker is both the effective target and the caster of the effect" (emphasis mine). This should see a potion—barring specific exceptions—pretty much always ignore SR.
In other words, it's the potion drinker that matters. The creature feeding the potion to the potion drinker doesn't matter: the drinker's still doing the drinking.