Playing TRPG mod on Tribes version 1.11:
-Run TribesRPG111 shortcut
-Click Options, Click Video, Click on the arrow dropdown for Fullscreen Resolution
-Select the 1024x768 resolution. This is the best resolution to use for v1.11
-Select Host Multiplayer and select the RPG mod mission type
-Select rpgmap1 or rpgmap 5 and click host
-the deusrpg hud should auto scale to fit the 1024x768 resolution

Playing TRPG mod on Tribes version 1.30:
-Run TribesRPG130 shortcut
-The resolution is set in your Config folder in autoexec.cs
-You can edit the lines:
$WSWidth = "1920";
$WSHeight = "1080";
-Select Host Multiplayer and select the RPG mod mission type
-Select rpgmap1 or rpgmap 5 and click host
-the deusrpg hud should auto scale to fit the resolution you set in the autoexec.cs


Whats the difference between Tribes v1.11 and 1.30?
The main difference is the 1.11 shortcut uses the very old tribes resolutions (usually played at 1024x768) while the 1.30 shortcut can use the widescreen fix to run 1920x1080 and beyond.
There are also some TRPG servers that are running a 1.30 server and in this case you will need to connect on 1.30 client as well to be able to connect to their server.

You can also launch a server by navigating to the TribesRPG\RPG folder and launching the rpgserv application. 
The rpgserv app lets you change a bunch of settings for your server including the name, password, and much more. Click the 'Advanced' button for the full list of launch options.
Set the tribes.exe location in advanced settings to C:\TribesRPG or wherever you have the tribes shortcut for the mod.
If you have trouble running the rpgserv app try applying to same properties to it that you do to the other shortcuts.