Installing VRidge for GearVR is very simple and it only requires few click. First of all install SideloadVR for GearVR app from Google Play here.
Then open SideloadVR app and your OSIG should be automatically set.
However if OSIG wasn't validated then go to SideloadVR navigation menu -> Manual OSIG Setup and follow the instructions on your screen.
Once your OSIG is configured, search for "Vridge" (without quotation marks) in SideloadVR app and install prefered version of VRidge. Remember to use the same version of RiftCat client.
NOTE: Installation of VRidge for GearVR might be blocked by Android. To install it simply go to Phone Settings -> Security and check "Allow installation of apps from unknown sources."
After the installation is complete, look for VRidge for GearVR in Apps on your phone, open it and put your phone into GearVR and enjoy PC VR games on your phone!