DVD players aren't capable of opening and playing PDFs, so that won't work. Your media needs to be in .VOB format in order for your disc player to play it.

But you can add a PDF as an Extra on your DVD. Extras can't be seen when you play the disc on your disc player. But, if you put the disc into a computer's disc drive, you can browse to the Extras folder and view any files in there.

Extras can include things like PDFs, Word docs, full-resolution still photos, etc.