Does Radiccio support AirPlay?

For Apple Music sources:

Unfortunately, no. Radiccio uses Apple’s MusicKit framework to integrate with Apple Music, and MusicKit doesn’t support AirPlay on macOS. We have reported this to Apple (FB18130054) and we hope that Apple will address this in the future.

There is a possible workaround: You can change your Mac’s audio output at the system level, to send all audio over AirPlay. This will affect all apps on your Mac, not just Radiccio. You can find this in System Settings > Sound > Output, or by using the Volume/Sound menu in the menubar.

For all other sources:

Yes, you can choose AirPlay output with the AirPlay button in Radiccio’s toolbar.