To clarify, after you create a PDF you can use ‘pdftron.PDF.TextSearch()’ to search for any URL-s via regular expressions. This will give you a list of rectangles and URL strings that you can use to add Hyperlink annotations as shown in the Annotation sample.
To recognize URL links as well as email addresses use the following regex search pattern:
pattern = "((?:(?:https?|ftp|file)://|www\\.|ftp\\.)(?:\\([-A-Z0-9+&@#/%=~_|$?!:,.]*\\)|[-A-Z0-9+&@#/%=~_|$?!:,.])*(?:\\([-A-Z0-9+&@#/%=~_|$?!:,.]*\\)|[A-Z0-9+&@#/%=~_|$]))|([a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?)";
in TextSearch (http://www.pdftron.com/pdfnet/samplecode/TextSearchTest.cs)