RTF is a global modification that replaces all towns in the game.

If I remember correctly, you need to convert this GR2 file using 3DS Max 2008 with a plugin... but I'm not 100% sure.

That's right. Using a plugin for 3DS Max 2008, you can load the skeleton and animation. Alternatively, you can use the program (Noesis), which can also export animations to various formats (including FBX, SMD, PSK-PSA). This was discussed in the thread "Guide to adding a new model, animation, and creature to the HoMMV game" (on pages 22-24).