From the command line:

# yum install -y kde-runtime.x86_64 kdm @kde-desktop

Optionally, if you want to run KDM instead of GDM:

# systemctl disable gdm
# systemctl stop gdm
# systemctl start kdm

Note: This guide should work on Fedora 19 as well; but I haven’t tested it.

Source: http://marcofalchi.blogspot.com.au/2013/10/fedora-1920-install-kde-kdm-swith-from.html