There are a couple of ways to do this. The first being the easiest, you can go into your kcontrol, to your session manager, and check the box that says restore with previous session, so as long as that app was running when you rebooted KDE it would restart that application upon restart. Now it you wanted that specific application to start each time with out having to restore the entire session from previous desktop session. You could use this method
http://l10n.kde.org/docs/admin/autostart-and-runonce.html which is my preferred method. Running a restore session can sometimes cause errors. So the second is the recommended. Happy Linux!!!..