Step 4: Enter transaction details
Enter the amount of bitcoin you would like to send and select the account you would like to receive to. Then, hit "Generate Invoice."
Step 5: Lightning Invoice Generated
You will now see a Lightning invoice, represented as a QR code and a long alphanumeric string. Pay the invoice from your non-River Lightning wallet by scanning the QR code or by copying and pasting the Lightning invoice text.
Complete the transaction from your other wallet and you're all set!