I had this situation as a white hat during a freshman game. SWC had first and goal at the one and the RB lined up directly behind the QB. At the snap, the QB attempts a QB sneak but is held up slightly until the RB charges him from behind and pushes him over the goal line. Positioned as the Referee, I threw the flag and called a penalty for aiding the runner. The SWC coach was angry and called me over for an explanation. I informed him as to what I saw and the basis for my call while also telling him it is within the rules to push the pile; you just can't grab and directly push the runner from behind. He disagreed and said they do it all the time and other officials never call it. He asked me to send him the rule and gave me his email. Would you advise I send him Rule 9 Section 3 Article 2 from the rule book? Would you advise I not make this call in the future?