Hi Andrew,
in which context are you trying to use boost libraries within Rhapsody?
I'm assuming the following:
- you are trying to develop a C++ application within Rhapsody Developer Edition for C++,
- in Rhapsody you created a component, which selects the packages, which contain the classes, that shall build your application in your scope,
- the component contains a configuration, which selects your build environment, like MSVC or Cygwin, or MinGW, or any other,
- now your classes shall include headers like <boost/json/src.hpp> and you want your compiler to find these files during build process.
There are at least three possibilities to achieve this goal:
1. use the entry fields of your current configuration to add path definitions exactly where needed:

2. Modify Properties of your selected build environment (in my case Cygwin) on project level to add such an Include Path by default for all configurations (useful if you defined several configurations using boost libraries), e.g. the template for the makefile content:

3. Create a new environment, which contains all required settings to build applications based on boost libraries automatically.
Such an environment can be easily added via siteC++.prp in Rhapsody's Properties installation folder.
Afterwards you can select an environment like CygwinBoost or MSVCboost from the Environment drop down list in your configuration.
P.S. do not forget to do the same for the libraries to be linked.
Hope this helps,
Martin.