I recently installed a new RipCord rest and it is working great. Broadheads and fieldtips are grouping tight. Now I need to quiet it down a little. Any suggestions?

I use the sheet style adhesive backed moleskin on ther entire shelf and on the rest for my trophy taker...

Moleskin helps, you can also get "MOLE-FOAM" if the Moleskin doesn't quiet it enough, and darken it with a black/brown/green marker. Mole-Foam is meant for feet, but has many uses, and is a little thicker than Moleskin.

How much is the moleskin going to affect the tuning of the bow? I just got the broadheads to group with the fieldtips.

Very little, you can put the moleskin on your riser first to see if it helps enough that you're satisfied, then consider the rest if that doesn't cut it.

You didn't say and no one has asked but what exactly about the rest needs to be quieter? What is making the noise?

The arrow being drawn back against the rest makes a noise.