Configure the RD Gateway to send RADIUS authentication to an Azure Multi-Factor Authentication Server. 

1. In RD Gateway Manager, right-click the server name and select Properties.
2. Go to the RD CAP Store tab and select Central server running NPS.
3. Add one or more Azure Multi-Factor Authentication Servers as RADIUS servers by entering the name or IP address of each server.
4. Create a shared secret for each server.