Safety or Touchback-A Force Issue?

[mbyron]

Originally Posted by Bob M.

PLAY: K's punt from A's 5 is blocked and comes to rest where either (a) K10 or (b) R6 muffs the loose ball into K's endzone and across the sideline. RULING: (a) Safety since it is K's force that put the ball into K's end zone where it became dead. In (b) it's a touchback since it was a new force by R which sent the ball across K's goal line.

A touchback in (b)? So K gets the ball back at their 20? R loses possession of the ball because they blocked a punt into the EZ? I'm not following this.