A complete integration guide is available on the PagerDuty website.
To enable the PagerDuty Integration, the PagerDuty Integration Key must be configured in the Organization Advanced Parameters (Menu -> Organization Name -> Change Organization's Advanced Parameters -> PagerDuty Integration Key).
Once configured, the Send Test Notification Link below the Integration Key can be used to send a test message to Pagerduty to validate that the integration is successful.
How to generate the Integration Key?
Inside the PagerDuty portal, configure a new Service or a new Integration to an existing service. The Integration Type must be Events API v2. The Integration Key will appear after saving the new Service or new Integration.