Use the following code in your funnel:

<script>
  window.review_access_key = '{{custom_values.rms_access_key}}';
  window.review_template_id = '10'; // reviews Direct
  window.review_embed_id = 'YOUR_ID_HERE'
</script>
<script src="https://ratemyco.s3.amazonaws.com/ghl_reviewpanda_funnels.js">