Here's a few other freqs that have been associated with Skywest/United Express air to ground.
As suggested already, searching is probably the best thing to do. Start monitoring about a 1/2 hour before arrival. Contact will probably be closer to 10 mins out. It's possible that station ops may only have a handheld air radio with such a small operation. You may not hear Skywest PRC ops unless you are very close to the airport but should be able to hear the aircraft call while airborne.