Facebook detects the URL and displays the link address. Unlike with links to Web pages or blog posts, Facebook does not parse information or thumbnail images from the linked PDF document.

Safari can use a standard Print dialog and preserve links in a PDF it creates. Visit a web page in Safari. Select File > Print.

Outlook 2013 supports the inclusion of JPG, GIF, PNG and BMP image files directly in a signature. To add a PDF image, you must include it as a Web link.