Free Kick

I did a lot of research on this earlier this season.

The "free kick" after a fair catch is legal in the NFL and in High School but is not permitted in college.

The opponent must align 10 yards back just like a kickoff, yet if you kick the ball through the uprights, you get 3 points. You would also line up as if kicking a KO, but you would have someone hold for your kicker.

Generally this would only be used at the end of a half when you have your opponent pinned deep and you fair catch their punt. You kick from the yard line the ball was caught on.

Does there need to be time showing on the clock? If the team punts it and the opposing team fair catches with 0 on the clock is the game over or do they still get the free kick situation with 0 showing?