atriaze So it sounds like you're using the meson macros, when it is actually using cmake as a build system (see also their "Manual Way" of compiling here)
So what you actually should be using are the cmake macros, see here for a reference. In fact, since we have rawtherapee in the repo, you can just take a look at and copy from that paricular package.yml: https://dev.getsol.us/source/rawtherapee/browse/master/package.yml
This also doesn't look like it would be the easiest package to compile for a beginner, but maybe with the template of rawtherapee it's doable.
