If OpenGPG is functioning correctly you will have to give the pass-phrase every time you send a document that is to be signed. This soon becomes a pain, and the way out of that is to configure gpg-agent, which comes with kdebase-common package. Unfortunately, the install does not pick up the need for pinentry-qt(4) or pinentry-gtk (KDE or GNOME), so that has to be installed separately. The config file for gpg-agent is written to by KMail's settings.
