Kickoff on Receiving Team's 10 yard line

[Robert Goodman]

Who said R's restraining line can't be in their end zone in Fed? You can use the chain to mark the neutral zone, although I'm told here that's not proper mechanics.

What team K should probably do is just a short free kick, short of the goal line. What can team R do? And even if it goes out of bounds, according to what was discussed here a few yrs. ago, the only choices R has are:

penalty & have the kick repeated, and
accept possession at the dead ball spot.