Once you have set your base rate for your roomtypes, this will show on the booking engine mybookings, from there you can have a different rate on each channel, derived from the base rate
1. Navigate to the gear icon > Channels.
2. Click on the green button of the chosen channel and press "Next" until you reach the "Base Rate Adjustment" page.
From the "Base Rate Adjustment" page you can encrease or decrease by amount or by percentage