The problem here (and I might be wrong - I'm a little sleepy today) is that you are trying to rank players with respect to how many other players there are, when we're not talking about a specific tournament, but a whole set of tournaments that might have different sets of players.
For example, a single tournament might have 8 players. It's easy to award points based on a player's final rank and how many players there were. I think yours would be something like (100 / n) * (n-r+1) * 1000. But that's because you already know where the player ranked (and associatively how many other players there are).
For stats, the point of the formula is to come up with a way to rate players based on disparate performances. How can I rate this guy's performance in 6 tournaments, and how can I rate this other guy's performance in only 2 tournaments, and place them on the same scale? And unlike the Points for Playing formula, you don't already know how this player ranked with respect to others (which would make it easy), you are creating that rank.
I'm not saying this can't be done, I just don't see a way. The formula doesn't know how many other players are being ranked, so it can't evenly space those rankings out over a particular scale.