Understand what happens if you try something and lose the ball but what happens if you end up 50 yards down field, tackled then knock on the ptb.

That would be a scrum h&f to the opposition as the "advantage" would have finished when the tackle was completed

Anyone seen a penalty for an incorrect ptb or is that just for pre season games?

The ball comes right back to the scrum.
It is to try and create extra skillful moments.



EDIT-Wait you said at the play of the ball well that is after the tackle so if would be as normal because as soon as the tackle in completed the advantage is lost my mistake.

I do think it will get messy (As in upset fans/coaches) when a team goes for the spectacular play and then drop it over the line only for the ref to then bring it back for the scrum.

I've seen plenty.

There were 2 on Sunday (I think).

The one Jason Crookes gave away was ridiculous, he ran about 10 yards to play the ball after the tackle had been made.