I've never seen Microsoft's RDP able to connect to a Mac directly although the last time I tried was quite while ago. It sounds like you've tried this already and simply want confirmation it doesn't work? TightVNC, UltraVNC etc are able to connect to macs that has the option enabled in the Sharing Preferences pane. All of these VNC programs of course use VNC which you're not interested in. I'm guessing the reason you're asking the question is because your network restricts VNC traffic? In the networks I've worked in where VNC is restricted I've found SSH is allowed. If that's the case for your situation I have been successful using VNC via SSH. There are some tutorials on the internet outlining how this is done which you may find useful and/or more suited to your needs?
There's also this app on the app store (I've not tried it) which might help you better?
https://itunes.apple.com/gb/app/jump-desktop-remote-desktop/id524141863?mt=12