To link with SDL_ttf you should use sdl-config to get the required SDL compilation options. After that, compiling with SDL_ttf is quite easy. Note: Some systems may not have the SDL_ttf library and include file in the same place as the SDL library and includes are located, in that case you will need to add more -I and -L paths to these command lines.
Simple Example for compiling a source file:
cc -c `sdl-config --cflags` mysource.c
Simple Example for linking an object file:
cc -o myprogram mysource.o `sdl-config --libs` -lSDL_ttf
Now myprogram is ready to run.