Thank you Jason. Unfortunately this didn't fix the issue. I inserted the two lines:
<?php require_once("WA_ValidationToolkit/WAVT_Scripts_PHP.php"); ?>
<?php require_once("WA_ValidationToolkit/WAVT_ValidatedForm_PHP.php"); ?>
The files were actually not generated either in the root of my site so I had to copy them from another Webassist project to this location.
Either way, I still get a blank page on load with no errors displayed. I just get a page with
<head></head>
<body></body>
and that is it.
Your assistance is appreciated.