I wasn´t able to find a tutorial so I try to describe my problem briefly.
I recorded a video with a green screen and using the chroma filter worked great. However I want to make the person smaller in the video. But if I use the filter “Size” it doesn´t scale down just the person. So if I scale it down, you can see the outlines of my greenscreen and everything.
How do I change the size of just the person I cropped with chromakey?
We don’t see much in the image you uploaded… Too small
But if I understand your problem correctly, I would suggest to add a Crop: Rectangle filter.
Add it bellow the Size, Position & Rotate filter in your liste of filters.
Make sure you click on the Transparent button and reduce the size of the rectangle until it hides those outlines.
