If you need to pick an F series Schlage lock, you don't really have to pick it to the open position, but try picking it to the "locked' position (sometimes it works better to pick it to the "close" side) and then, as you are holding the plug in the locked position, use a hooked poke tool to depress the knob retainer and remove the knob.
You can use a pair of sharp pliers to turn the actuator inside the knob to open the door. If the customers has the keys to the lock within reach, re-install the knob and turn the plug back to the normal position. If the keys are not to be found, leave the plug in the picked position, remove the cylinder from the knob, remove the clip and make a key, or simply re-key the lock, whichever more desirable for the customer. Check out the following link for more useful locksmith tips.
