The link shows that you need a connection file, and that will allow you to connect to the remote server with few keystrokes.
You create/edit the connection file and write the batch file, call it R.BAT and put it in c:\Windows
Then press Windows + R, type R and press enter. You should be connected.
The way I read it the link shows that with a connection file all you need is this:
@echo off
mstsc "%userprofile%\desktop\server1.rdp"
where you create the server1.rdp on your desktop. You may be able to just double click the RDP file if the associations work.