Link annotations create hyper-links to other parts of the same document, to pages in other PDF documents, to web addresses, email accounts or to other files on your system.
You can create link annotations by issuing the a command from the
menus and dragging a selection on the page over the content that you
want linked. If the content contains text, the link will be made to
fit the text neatly. You can also select some text first and then
issue one of the link creation commands. Once the link is created you
can set its destination in the Dynamic Annotations Inspector. See the
entry in the chapter on the
Inspector Panel for more
information on setting link destinations.
If you want to highlight a link annotation by underlining the link
object you can do so quickly by selecting the annotation, then
bringing up the contextual menu of the view and selecting
Selected Annotations > Underline.