Rhombus integrates seamlessly with Google Tag Manager.
Log in to Google Tag Manager and navigate to your website's Workspace, and click Add a new Tag.
Select the 'Tag Configuration' rectangle box, then click 'Custom HTML' on the right side navigation.
Paste the code snippet you're given. E.g.
var rhombusSiteId = 123456;
If you have not received a dedicated script tag please contact your account manager or firstname.lastname@example.org
Click 'Save' and you should be asked to create a Trigger. Select 'Add Trigger.'
On the Trigger page, click the default 'All Pages' item in the table. This will take you back to the tag, where you can click 'Save' again.
You're done! Rhombus will now fire on whatever pages your Google Tag Manager Workspace is connected to.