All you have to do is take the bg of the sig in a new document big enough to fit the render. After you make the new document, place the render on and blend it or w/e. Then delete the white part around the top part of the render. Make sure u have a transparent bg tho. Save it as a png. And your done.
Critque: Not the best bledning in the world mate. Also the text is hard to read.