external.php footer syntax help

[Budget101]

I would like to add my own footer to the external.php so that it is automatically called when a feed posts. I'm assuming I can add this in line #670 (Under RSS1). However, my syntax appears to be off. . .

PHP Code:

$xml->add_tag('footer', $thread['prefix_plain'] . unhtmlspecialchars($thread['title']), is a post from $vbulletin->options['bburl'] ")); 


I am trying to create syntax so that the "Footer" appears in this format:

THREAD TITLE is a post by MEMBER NAME at MY DOMAIN NAME.

Could someone please assist me with the correct syntax to use to call these variables?