Can't find "phidget21.h" in Qt Creator Project

[CRAZEERUSKEE]

Hello,

I have a 1044 that I am trying to run with a Qt creator project. Running Spatial-simple.c from Terminal works fine, but when I copied the exact same code into a Qt Creator project, it says that it can't find the phidget21.h header. Looking in my files, I can't even see where that file is or if it even exists (I'm assuming it must since the test code works without any issues). How do I find the path to it? I'm on a Mac if that helps.

Thanks in advance for any help!