Increasing margins of all pages in a pdf file

Here's what I ended up doing: I added a thin Header/Footer to every page with Adobe Acrobat Pro 9. There's an option in the Header/Footer dialog that compresses the contents of every page to make space for the header/footer, which is exactly what I wanted.

I needed to shift down the text on a 109-page pdf so it would print to labels. I was able to do it in Header/Footer. Click on Tools > Pages > Header & Footer > Add Header & Footer. After you change the margin you want adjusted, click on Appearance options and select "Shrink document to avoid overwriting the document's text and graphics."

You can definitely increase the page size: Go to the Document menu -> Crop Pages and put a larger size in the Change Page Size section.