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

But doesn't he explain how he did it, or haven't you asked yet?!

I didn't ask, and I've already figured it out myself (I checked his mod).
Here, you need to change the alpha mod to AM_TRANSPARENT.
Now, we need to deal with the issues caused by this parameter - the sleeves are visible through the shoulder pads! We'll have to leave something highlighted.