Table of Contents
synaptiks actually consists of two different applications, a service and a System Settings module.
The daemon starts during logon and controls the touchpad. Make sure, that the synaptiks daemon is enabled in the Service Manager module in System Settings.
The System Settings module configures the daemon and the touchpad. It is located in ->->.
Additionally a Plasma applet is provided to display the touchpad state on the workspace:

synaptiks provides a global shortcut Ctrl+Alt+T to switch the touchpad on or off. If you are using the synaptiks applet, you will notice a red cross appearing, if the touchpad is switched off:

You can also use the applet to switch the touchpad off. Just open the applet settings dialog:

Caution
You can of course not use the touchpad to switch the touchpad on again this way!