Fill / outfill speakers need a delay offset so their sound arrives at the listener at the same time as the mains. Enter the distance gap and get the delay time.
Measure the distance from your main PA to the delay fill speakers. Enter that distance. Set this value as a positive delay on the delay fill channel in your console or processor.
Add 5--20ms of extra pre-delay (Haas effect) to make the sound seem to come from the mains, not the fills.