Attaching PDF to User Notification Clarification

I've seen this very helpful post here: http://www.gravityhelp.com/forums/topic/use-pre-selected-file-as-user-notification-attachment#post-53767

but, how do I set this up for a specific form? I see where to change the file link. For example, I'm using this for form #19. Where do I put that in the code? Thanks!

Hi, I'm using the code below to send out a standard attachment with each user notification. The notifications get sent out, however, with no attachment. Any idea what I'm doing wrong?

# add attachment feature to user notification
add_filter("gform_user_notification_attachments", "add_attachment", 10, 3);
function add_attachment($attachments, $lead, $form){

    //getting wordpress upload folder
    $upload = wp_upload_dir();
    $upload_path = $upload["/var/www/2xy/data/www/messagehouse_2012/wordpress/wp-content/uploads/temp"];

    $attachments = array();

    //add a file from the uploads folder
    $attachments[] = $upload_path . "/test.pdf";

    return $attachments;
}

Yes. Thank you.