For a more in-depth article, please refer to https://lido.mixbytes.io/docs/guides/transfer-your-ksm-to-moonriver.
To stake KSM, users must first transfer their KSM to the Moonriver network.
Head over to kusama.lido.fi and select the Transfer tab.
Connect your wallet.
Enter the desired amount of tokens that you would like to bridge.
Confirm the transaction in your wallet.
Ta-da! You have successfully bridged your KSM and are now ready to stake with Lido.