Add Station to Siri
Any station can be added to Siri so it can be started by saying a phrase like "Play WKRP".
You configure the action using the station's info view on the platform you're using, start by selecting a station to play it. Then:
iOS: Tap on the Info button in the upper-right corner of the screen.
tvOS: Swipe up on the remote to reveal the control panel, then select the Info button on the right.
macOS: Click on the Info button in the lower-right corner of the window.
From the station info screen, tap on the "Add Station to Siri" button to select a spoken phrase for "When I say". By default, the name of the station is used, but you can set this to whatever you want.
Leave the "Do" action as "Play Station" and press "Add to Siri".