Step 2 - Look under Cross Chain Assets and you will find Statemine RMRK. Click deposit.
Step 3 - A popup will show up asking you to connect to the Polkadot.JS extension.
Step 4 - Click to connect and a new dialog box will pop up.
Step 5
Leave the Origin Chain on Statemine. Select the Statemine address that is holding the $RMRK. Enter the amount of $RMRK you want to send to Moonriver Sign the transaction by entering your wallet password.
And that’s it 😃