Combining PDF and GIF

In general, a GIF file is an image file, so the image will be in the document when you "combine the PDF and GIF". However, I assume you are talking about one specific flavor of GIF images, and that is animation of the individual frames that are stored in the GIF file. This will not work: Acrobat will only display the first frame when you import the GIF image. You could convert the GIF to a movie and then import that and loop it.