Here's what I can come up with to put in the 'points for playing' box: n-r+nh
n=number of players
r=rank
nh= number of hits (knockouts) a player has earned.
Since you have the first out as -5 points, I would make a prize, non-monetary, points, -5, and award award it to the first person out. I'm not sure if there is a way to add it in to the formula, but if there is, I'm sure someone else will let you know. At the very least, this will be a good start.