[Upnorth]

It is a foul for roughing the kicker if a defensive player: contacts the plant leg of the kicker while his kicking leg is still in the air; or. slides into or contacts the kicker when both of the kicker's feet are on the ground.Aug 30, 20

This is supposed to be straight out of the official's handbook; however, I doubt its' legitimacy.
1)  The statement just before this rule said that there wasn't a lot of information about this rule.
2)  There's a typographical error in the printing of this rule.

You can't even trust google these days!!

Yes I found this as well.  Which seems like the call might of been correct. But please if someone finds a more clear rule please let us see it.