yes you have to turn the knob
Top
Up
Turn
On
Ride
Off
but it's much cheaper and easier to fit than a scottoiler
there is other cheap alternative:
loobman : same principle except that you press the tank to send oil in the delivery tube
cameleon oiler: electric and pre-set, so turns itself on when you turn on the bike (I was quite tempted by this one...but it's way too expensive)
lubetronic, pro oiler, and probably others ....
Quite a few others (see the middle of
http://www.webbikeworld.com/motorcycle-oil/ )