When using V-ray with a host application like SketchUp having multiple screens can really help productivity, from setting up the camera, making changes in the host software or anything else it's essential to have both views open at the same time. 

An error that often occurs is when you move V-Ray to your second screen it simply disappears and requires a software restart to show up. To resolve this find the V-Ray Preferences, for SketchUp this is under Extensions > V-Ray. 

In Preferences untick 'Parent Frame Buffer', you may be prompted to restart the host app, which is required, ensure to right-click the hotbar icon and then Quit to ensure the software is properly closed. 

Open up the software to test the functionality is as expected and enjoy rendering on the second screen! 

If this does not work for any reason please reach out to the team where we can advise further for you.