Kevin, I'm Tim. Can you explain to be in more detail of what you want? Are you asking how to set up RDP for users to use from out side the network? If so what securit needs do you have? Do you have a VPN? Are you ok with using alternatives to RDP id it helps with security? The more detail provided, the better.
Well, we can do RDP or VLC and punch a whole in the firewall......but when you do that, you usually want a VPN, but not always. We here at justanswer use https://www.screenconnect.com, and it is by far the best remote software I have ever used, far better than even RDP, You can chat, use Mic/headsets, transfer files, even reboot servers into safe mode, etc. That's what i would do, and for two users its like 35.00 a month, and you get to avoid messing with the firewall or VPN, its all over ports 80 and 443 which you already have open.
You can also run stuff from your "tool box" on your off site PC, so in my case, I have a bunch of server Diagnostic stuff loaded that i can run from home, on remote servers, its as fast as your connection, and frankly, more reliable than RDP. RDP often has to have its PID killed to start working again, and obviously that has to be done in person. I have nothing against RDP, its just not the best, ***** ***** is for sure not the worst.