Add external Javascript file to Details page

I've been trying to add a Javascript widget (below) to my app on a record details page using the code examples in the Help Desk Solutions page here but without success....

I know the correct scene / view I need it on from my builder link (below) - and we're not that bothered on the location of the widget (just at the bottom of the page would suffice)

All the code examples form the help page were to do with editing elements, rather than a simple adding of an element which is what we're after. I'm hoping this is possible without needing a Web Dev to set it up for us?

The script as provided form Zoopla (here) is:

<div class="zoopla_widget" id="zoopla_values"><div class="zoopla_header">Home values in England</div>

<script type="text/javascript" src=""></script><div class="zoopla_footer"><div class="zoopla_powered"><span>Powered by</span></div>

<a href="">England house prices</a><div class="zoopla_get_this"><a href="" rel="nofollow">Get this widget</a></div>




Any help / guidance would be much appreciated.