How can I save a logo with all the whitespace according to pre-selected template format?

Hello!

I have a logo I've created using A4 template. How can I save it with the whitespace, according to A4 format, even the logo does not use all the A4 "rectangle"?

I'd like to have an image with all the whitespace up to A4 borders. If I make a selection of my logo and use "Save only selected", I will have something like this in the end:

Thank you in advance!