[DJ_NV]

The better way to state this is that the protection afforded to R under the fair catch rules are no longer applicable once the ball touches the ground.

The rule is 6-5-6 (in NF) and the key words are "in flight", which is defined 2-1-3 as a ball that has not touched the ground. Therefore, you can infer that if that ball has touched the ground, then 6-5-6 (and its association protection of R) do not apply.

Also note that the KCI restrictions are also no longer valid if R touches (think muffs) the ball, even though it hasn't touched the ground.

To answer your question about when the kick ends: The kick ends when one of two things happen. Either 1)the ball becomes dead by rule (goes OOB, etc.) or a player gains possession of the live ball. IF K gains possession beyond the NZ, then 1) and 2) happen at the same time. If R gains possession, the ball is still live (the down is not ended) but the "kick" has ended.

Secondly, there is no rule that states that R is protected until the "kick" has ended. R is only protected as long as certain things have happened, mainly:

1) a valid FC signal was given
2) the ball has not touched the ground
3) the ball has not touched a Team R player

If any of those things happens, then R is not protected and a foul for KCI cannot occur.