resizing a pdf file for printing

I download sheet music and want to be able to change the physical size of the pdf images to fit a page. Sometimes they print out too small and can't be read. Sometimes they print too big and some is cut off the page. Checking the "scale to fit paper size" option in the print dialog box doesn't do anything. I don't have a pdf editor, just Preview. I tried copying the image and pasting into a Word document and then resizing, but there was too much degradation of the image.