Assuming an NFL receiver catches a ball and maintains possession, if he hops twice on the same foot before going out of bounds, does it count as a catch? Does the rule book specifically say it needs to be two distinct feet?
The NFL rule (8.1.3b) is written as "touches the ground inbounds with both feet or with any part of his body other than his hands;"
So you need both feet to touch inbounds, or one foot and and a knee, etc.
See NFL rulebook online.