How do I correct this problem?

Using a plastic coupler, which is a little more pliable, often helps stop stubborn drips. Works like teflon but doesn't require redoing every move. And as mentioned, the pressure reducer should be on the shore water valve to protect your hose too. And it's weight might be contributing to the drip...if it's there at the city water inlet.

Wiping the area with vinegar will remove the white stuff, then you can watch for where the build up is coming from. But it kinda looks like both your valves need to be removed, cleaned, and wrapped with teflon tape.