Change page size

[RedMser]

Hello, this tool looks very capable and promising.
One feature I've not been able to find after going through all of its menus is a way to change the page size.

In my case it would simply be a matter of adding a bit of whitespace to the right of a page, so I can add text annotations next to the main body of the page (leaving the existing content of the PDF in place).

I found File -> Properties but those seem to be read-only. Also from what I understand, PDF allows changing the page size per page, though in my case I don't need this.

Let me know if I missed something, and thank you for your hard work!