You can add a Pushover Contact type from the Manage -> Contacts section of the RBLTracker Portal.
Select “Pushover” from the Contact Type drop-down, and enter your Pushover User Key in the Contact Information field. Your Pushover User Key is available from your main Pushover account page:
Your Pushover User Key is automatically confirmed against the Pushover network, so your new contact is ready to use right away.