Two Weapon Fighting or Rapid Shot with Wrist Launchers

Two Weapon Fighting or Rapid Shot with Wrist Launchers

Wrist Launcher, Heavy

I have the rapid reload feat for this weapon and since you can wear one of these weapons on each forearm and functions much like a hand crossbow, that free loading both would be easy both hand are free, unless holding something. However I’d like to be able to you use both in combat together, but confused as how to do it. Do I use it Rapid Shot or Two Weapon Fighting.