After a Punt Hits the Ground
 

I saw serveral times this weekend in college and NFL a punt hits the ground and the returner field it for better field position.
My question can K block the R to prevent him from fielding a punt after it has hit the ground? (Fed) I think K can.

Not sure and don't see this too often. I would think K would be going for the ball not the R.

K is always restricted from contacting R in a way that restricts his ability to catch the kick. K is also restricted from contacting R once a fair catch signal has been given. Once the ball hits the ground R can't catch the kick anymore and thus those restrictions are removed. However K can't just go and de-cleat R while the ball is bouncing around.