If your loads fail to knockdown the steel, once protocols are followed and it's determined your ammo is at fault, you will receive a 10 point penalty for each one left standing. This is in addition to not getting the points the targets had available.
PF refers to Power Factor. This is determined by multiplying bullet weight by velocity, divided by 1000.
A 9mm with a 125 grain bullet must go 1000 fps to make Minor Power Factor. (PF) If it's only going 950 fps, then you're shooting for fun, as no score will be calculated.
There is no chrono at the monthly matches, so the only consequence for running loads that are too light would be the penalties for failing to knock down the steel.
But don't worry about the details. If your ammo is factory equivalent, you won't have any problems.
Come on out!