I have a few clips (interviews) that was filmed in front of a white screen (like you would project presentations onto with a projector). There is no reference frame so I have to manually set a key point to key out the projector screen. When I key the footage I loose part of my subject (white areas in their shirt, name badge, parts of jewlery, etc.)

Is there any way I can tell Ultra not to key out a certian area (like masking an area not to be affected by the key)? I've played around with the sliders on the different tabs and can not get a good removal of the projection screen without loosing part of my subject.

I don`t have ultra, but if you are importing back into another NLE you could do your masking there, by using the source footage masked with feathering (the area of the subject you don`t want vanishing) over the keyed footage (make sure to export with an alpha channel). Just a thought.