Well you could use Word or LibreOffice to change the margins, you wouldn’t have to go for the full professional package. You won’t get quite as good a result from a traditional all-in-one word processor, but it won’t be awful (and it may be better than what Scrivener can do, if you aren’t using Word’s layout engine in your export settings).
That may be difficult since PDFs already have everything placed, more like drawn on a canvas than a text editor. There may be a way to change margins globally in something like Acrobat Pro, though I can’t imagine that’s any easier or faster than opening an RTF in a word processor and changing the source text before it is turned into a PDF.
Although it is not always up to date, we do try to keep this list current. We price the Windows version cheaper, and make no intention to say it is the same as the Mac version, which is years older. As we develop new features on Windows, that gap closes, as it has for some time now. But obviously we can’t do everything at once.