The current Virtual Keyboard solution on KDE ( maliit ) isn't working quite as much as i'd like. It only works on GTK apps, and only sometimes shows. When it does, it won't relaunch after dismissal untill you kill it. Add to that it's not as feature-dense as its windows alternatives.

I hear that they are working on their own plasma-keyboard, and I hope that will fix most of these issues, but I haven't had the tim to update my system.