Technically, it will be the plasmoid networkmanager applet, which replaced knetworkmanager.
If it does not show up, then:
Personal Settings → Startup and Shutdown → Service Manager
In the bottom panel, make sure that “NetworkManager User Settings Service” is checked.
Save the results.
Next: Right click on your KDE desktop, and make sure that widgets are unlocked.
Next: Right click on the system tray, and select “System Tray Settings”. In those settings, make sure that “Network Management” is checked.
You might need to logout from your KDE session, and login again, before you see the effects of the changes.
You should then see in the tray, either a red X (NetworkManager is not running) or an ethernet connector icon (you don’t have an operable WiFi card), or an icon that seems to be radiating upward (you do have wifi). That’s the icon for you networkmanager plasmoid.
Got it, thank you. NM User Settings Service is running. NM icon is checked (and appears in the tray). The “Enable Wireless” box is checked in Net Manager. Looks like this part is working OK.
When editing a wireless connection entry in NM, the pull down menu of interfaces lists a wlan0 that is disconnected. That is a problem of no kernel module loading, I believe, which I will pursue in another thread.