I'm new to OBS. I'm trying to avoid buying a second monitor. My monitor is 1920 x 1080. For my presentations, I want the video output file to only show half my screen (960 x 1080) instead of the whole 1920 x 1080. I am able to do capture and record half the screen which is a power point presentation that is annotated. However, when I view the recorded video afterwards, it shows the whole 1920 x 1080 where the left half is black and right half has my presentation. I only want the video out to show the left side. Is there a way to do that without buying a second monitor?