I am ok for it - what does it mean?
I disagree (with Yosef Baskin's answer). In this usage, I believe the person saying "I"m okay for chips." does NOT want chips. As in:
I'm okay for chips, but I'll go in on a cheese plate.
Similarly, when asking someone if they want refills, "I'm good" or "I'm okay" indicates that the would-be recipient does NOT desire any - she is already comfortable, and desires no more.