Touchback or not?

[BigGref]

Asking for thoughts on the following situation.

4th and 8 from midfield, K1 kicks a beauty all the way towards the endzone, R1 who was in position to catch at the 10 does the whole fair catch signal and lets the ball go over his head.

K2, coming from the side, runs parellel to the goaline and catches the ball after it bounces once at the 5, he catches it like marvin harrison (or other local WR), grabbing it out of the air at the 1, gets his feet down in the field of play, then his momentum immeadiately carries him into the endzone where he falls to the ground. So where do you put the ball?