You can add a custom link to the end of Like and Share by using the actions
parameter. For example:
$post = $facebook->api( "me/feed", "POST", array(
'message' => 'Testing custom search action',
'actions' => array(
'name' => 'Search',
'link' => 'http://www.google.com'
)
) );
print_r( $post );
Will produce: