Begin by selecting Trezor in the wallet connect dropdown.
This will prompt you to allow Radar Read access to your Trezor wallet.
This will export your public key to Radar so that you can see your token balances.
You can confirm that your wallet is connected in the wallet connect screen.
When placing a limit order you will be prompted to confirm the transaction on your Trezor.
When placing a market order you will be prompted to select the gas price and then confirm the transaction on your Trezor.