You should not get problems with dependencies and ports... do this:
cd /usr/ports/net/gtk-gnutella-0.95
make install clean
it should download and compile all dependencies. That will take a while. pkg_add is used to install pre-compile packages and thus faster, specially if you are installing KDE(or any other big guns) with a slow system. Other then that, I'd always go with make install clean
.
P.S: the above path may be wrong, if so is the case, use the search command to locate a port:
# cd /usr/ports
# make search name=gtk-gnutella