@David H A redirect rule proper (in the admin UI) uses an HTTP 301. There's no way to load any tracking code on the original page this way (Marketo could check the hit in their internal web logs, of course, but AFAIK this is never displayed).
However, you can use a JS redirect instead, allowing you to Munchkin and log the page view before doing the redirect. Make sure to load Munchkin in Simple mode, not asynchronous.
<script type="text/javascript">
document.write(unescape("%3Cscript src='//munchkin.marketo.net/munchkin-beta.js' type='text/javascript'%3E%3C/script%3E"));
</script>
<script>Munchkin.init('YOUR-MUNCHKINID-HERE');</script>
<script>document.location.href = 'http://my-offsite-page.example.com'</script>