To add a hyperlink or intra-document link annotation to a PDF Document page.

$doc = new PDFDoc($filename);
$page = $doc->GetPage(1);

// Create a hyperlink
$hyperlink = Link::Create($doc->GetSDFDoc(), new Rect(85.0, 570.0, 503.0, 524.0), Action::CreateURI($doc->GetSDFDoc(), "http://www.pdftron.com"));
$hyperlink->RefreshAppearance();
$page->AnnotPushBack($hyperlink);

// Create an intra-document link
$goto_page_3 = Action::CreateGoto(Destination::CreateFitH($doc->GetPage(3), 0));
$link = Link::Create($doc->GetSDFDoc(), new Rect(85.0, 458.0, 503.0, 502.0), $goto_page_3);
$link->RefreshAppearance();
$page->AnnotPushBack($link);

Add or edit PDF annotations sample
Full code sample which shows how to add or edit PDF annotations (e.g. hyperlink, intra-document link, stamp, rubber stamp, file attachment, sound, text, free-text, line, circle, square, polygon, polyline, highlight, squiggly, caret, and ink).