Another PSK question?

[BoBo]

K has 4th and 10 at K's 45.

K punts the ball.

While the ball is in flight or I guess on the ground past the exp neutral zone R4 blocks B5 in the back. The punt goes untouched in the end zone for a touchback.

1)R4 foul is at R's 30

2)R4 foul is at R's 15

What are the enforcement spots?

I am guessing in 1 it is from R's 20 1st and 10 @ R's 10

In 2 it is from R's 15 half the distance 1st and 10 @R's 7 1/2.

Any comments?

Hurt R the most theory???