In folder C:\Program Files\Silverfrost\FTN95\demo\win32\visualcinteroperability2\vcproject1
File 'vcproject1.cpp', line 81, extern 'C' DllExport void _FunctionArgumentsReference(int *i, double *x) the type of *x should be changed to 'float', which corresponds to 'real' in FORTRAN. Otherwise, the program will not run as intended.
Comparison of FORTRAN and C/C++ datatypes: http://www.yolinux.com/TUTORIALS/LinuxTutorialMixingFortranAndC.html