If you use Share->Share files, and you check the option for the page order, it will generate a new PDF containing only the pages the selected song uses. The same is true with Share->Export files (if you want to save the file somewhere before sending it). Printing will also work, although I would recommend using the sharing option over printing if you are just trying to send it through email, as the PDF generated through the Share feature will use the exact same pages from the original PDF (meaning all optimizations are kept in place), whereas printing re-renders all of pages to fit the desired printed page dimensions, so you lose image compression and other optimizations in the original PDF.
Mike
Mike