Watch the far sideline wing official from the beginning of this NFL play:
https://www.youtube.com/watch?v=FE9TKU2pGc0
At the snap, he moves slightly downfield to the limit of the expanded neutral zone, because NFL rules have a restriction on who can go downfield before a scrimmage kick; expanded neutral zone applies. Then the (first) kick is made, and he moves back to the original line, so he's in perfect position to rule on this very controversial play (regular neutral zone applies).