Defining Fortran compiler flags when building HDF libraries

Hello, I am able to build HDF Fortran libraries using CMake. However, I would like to specify a Fortran compiler flag that is not included in the standard distribution of CMake-HDF setup. Where do I define this flag in the CMake files? I am using the Unix distribution. Thanks for any help.

You can specify Fortran Flags using CMAKE_Fortran_FLAGS, for example: