"Tripping" of a runner is
NOT a foul under NCAA nor NFHS rules.
It might be a foul under NFL rules, but I'm drawing a blank at the moment on that rule code.
Here's your rule references:
RULE 9.1.2.b and c
b. No person subject to the rules shall strike an opponent with his foot or
any part of his leg that is below the knee.
c. There shall be no tripping (Exception: Against the runner).
So, did the player really TRIP the runner or did he swing his leg and strike the runner... There is a difference here.