What is great when using a PDF is you don't get the texture wrapping which is useful for images that you only wish for one instance of. Just make sure the program you are making a PDF from properly sets a page box or your experience may vary. In my experience I set up layouts in InDesign and output PDFs for Sketchup.
Mine is Sketchup 8, pro version on windows 7. At first I couldn't find the image file, but under the field "Name" of the file in Import window, you can change the file type, the default is set to dwg dwf, click on the arrow point down on this field and change to the desired one