What I do is to drag from somewhere near the botton edge to the botton edge, this is not a gesture to bring the taskbar up but since it leaves the pointer at the botton edge when you finish the gesture the taskbar pops out. To my knowledge there is no way to show it without using a workaround, looks like MS is trying to get the classic desktop deprecated...
Sorry for such a late reply, I hope this is still relevant.
Cheers.
Well unfortunately I have the same issue and I "hacked" my way through a solution. Perhaps someone else can make this better OR Microsoft could fix the keyboard to have a settings that makes the keyboard only come up on demand.
So you can stop and start services using batch files, plus you can disable and enable them as well. I wrote a couple of batch files that will start and stop the TabletInputService.
start_keyboard.bat has this in it:
sc config TabletInputService start= auto
net start TabletInputService
stop_keyboard.bat has this in it:
net stop TabletInputService
sc config TabletInputService start= disabled
Then you'll probably need to run these batch files as admin so I created desktop shortcuts to these batch files. Right-click the shortcuts, go to properties, click Advanced (under the Shortcut tab), click the Run as Administrator check box.
Now you can disable and enable when you want. I know it's a hack but this is the only solution I could think of. I've searched for a couple of days on Google for a solution and really this is the only question I've seen about this. Everyone just wants you to uninstall it or completely disable it.
Weird that Microsoft didn't think of putting in a setting called "only on demand" for this extremely obtrusive keyboard.
Best Answer
When you swipe from the right (to bring up the Charms bar) and select the Search charm, you get a text box. Touching it should show you the OSK.
Source: Microsoft's site about the Surface. Can't test this myself since I don't own a Surface, but maybe it is of help.