Correct call and good work by the R, yes. But RR sates that mechanics call for him to "look through" the QB - wrong! His first key is the tackle to the H side, unless they are in trips (or more) to the L side. On this play, they are in trips to the H side, so the right tackle was his key. Looking at the video, I think he is doing just that - not "looking through;" rather, he is observing the right tackle right from the snap. However, even if his key had been the left tackle, there was nothing happening there, so I believe he'd have come off that action quickly and picked up this obvious foul, anyway.