How to include grid in rendering?

hello can someone please tell me how I can include the grid in my rendering?

I realise it can be done with screencapturetofile but my issue is that screencapturetofile doesn’t produce an image of high enough resolution…so I’m looking for a way to do with by rendering…any help would be much appreciated. thanks.

I don’t know how to do this in a rendering, I’m afraid, but the ViewCaptureToFile in Rhino 6 for Mac does allow you to specify much larger resolutions than Rhino 5 did.