You're looking at the wrong file. I haven't touched the file that sits in the directory.
The injFX_settings.h file you want to look at is the one inside the injFX_Shaders folder, not the one in the directory. It should be #define USE _ANTI_ALIASING 1 in that file. I just checked it.
This is what it should look like:
I can't be bothered with taking a hunded pictures of my sliders again but they all correspond to the same settings. The anti aliasing sliders are all at maximum (all to the right).
So that one in the directory below is not needed? Or why do you have it there?
I can see that FXAA is set to 1 in the file in the subdirectory.