- Open the Mycelium wallet app and go to the "Accounts" page (unlock if needed)
- Click on the Account that says "contains private keys" then Click on the 3 little dots in the top right corner and select "sign message"
- Enter your pin again to unlock the address list, click on the address you want to sign and this will open the page for you to sign the address.
- Once you have signed the address copy the signature and text to your clipboard.
(remember to include the date and exact reason you are signing the address)