I would try a stamp option. This way, I am able to sign a pdf with a facsimile (jpeg file). It can be put anywhere on the page as a box. The only problem, it is not embedded and can be removed in Acrobat, but not in Reader, which most people have.
Tools>comments and markup>stamps>create custom stamp. In the dialog box, browse for the logo file (gif, jpeg, etc.), hit OK and then you will be able to name the stamp (in the favorites) and place it anywhere you want and resize if need be.