how to enable

First time use

"Alexa, ENABLE rainbow f.m. skill"

Subsequent times after enabled

"Alexa, PLAY rainbow f.m."

Alternatively enable manually

here

Alexa (more info) 

Ask your assistant

"Talk to Rainbow FM"

Available devices

Android 6.0+ TVs
Google Home
Android 5.0+ phones
iOS 10.0+ devices
Headphones
Smart Displays
Android 6.0+ tablets

Google assistant (more info)