How did you compile the file?

By typing make but you can see the exact 4 commands it ran in my post. The contents of f.c and f.tm were taken from above.

Another thing you may want to check is the exact path to WSTP on your system, in particular whether it has Contents/SystemFiles/Links in it or just SystemFiles/Links (for me with version 10.0 it was the latter).

Right now my make file is giving the following error:

Undefined symbols for architecture x86_64:
  "_WSMain", referenced from:
      _main in f.o
ld: symbol(s) not found for architecture x86_64

So I've been compiling executing the different commands in the make file. The -stdlib=libstdc++ is the EXTRA_CFLAGS which appears only in the second command. The error I showed earlier comes from the first command:

cc -I/Applications/Mathematica.app/Contents/SystemFiles/Links/WSTP/DeveloperKit/MacOSX-x86-64/CompilerAdditions ftm.o f.o -L/Applications/Mathematica.app/Contents/SystemFiles/Links/WSTP/DeveloperKit/MacOSX-x86-64/CompilerAdditions -lWSTPi4 -ls tdc++ -framework Foundation -o f

I just made that adjustment and get an error that starts like this:

Undefined symbols for architecture x86_64:
  "std::__basic_file<char>::is_open() const", referenced from:
      WSTP::MLLog::logSelectorToFileWithName(WSTP::mllogselector, char const*) in libWSTPi4.a(mllog.cpp.o)
  "std::basic_stringbuf<char, std::char_traits<char>, std::allocator<char> >::str() const", referenced from:
      mlopen_argv(ws_environment*, long, char**, void*, void*, int*) in libWSTPi4.a(mlopen.c.o)
      WSTP::MLLog::~MLLog() in libWSTPi4.a(mllog.cpp.o)
  "std::basic_ios<char, std::char_traits<char> >::widen(char) const", referenced from:
      feature_greeting(ws_environment*, WSLink*, device_kebab*, _queue*, feature_set*) in libWSTPi4.a(mlgreet.c.o)
      WSTP::MLExceptionMessage::print(std::ostream&) const in libWSTPi4.a(mlexceptions.cpp.o)
      WSTP::initSyncObjectDir() in libWSTPi4.a(mlplatformthreads.cpp.o)
      WSTP::MLLog::~MLLog() in libWSTPi4.a(mllog.cpp.o)
      WSTP::MLLog::operator()(WSTP::mllogselector) in libWSTPi4.a(mllog.cpp.o)
      WSTP::MLExprLog::writeContentsToStreams(WSTP::MLExprLog::mllogdirection&, bool, std::basic_ostringstream<char, std::char_traits<char>, WSTP::MLStdAllocator<char> >&) in libWSTPi4.a(mlexprlog.cpp.o)
      WSTP::MLInterfaceContainer::PrintInterfaceContainer(std::ostream&) const in libWSTPi4.a(mlinterface.cpp.o)
      ...

It may be the same exact one I had earlier