I am making a holiday greeting card. I have 16 very larged photo images "linked" (not embedded) into the card. The original images are very large (e.g. 4500 x 3000 px, 10mb) but I've placed them fairly small in the final card (only about 2" x 2" printed). Therefore, I likely don't need the full resolution of the original photos. I need to generate a final file that I can send to an online print shop, something that is ideally 10-25Mb in size, probably pdf. Can anyone help me figure out how to prepare the final file for export to pdf to generate as such? Right now, the final file is 275Mb because it is embedding the full size of each of the 16 images.
I'm on Illustrator CS6 on Mac.
Thanks for any / all help!