Running lane?
 

Batter runner running inside the base line makes contact with F3 playing up the line for the bunt, F4 fields a ground ball and and takes the ball to first on her own. Do you have a running lane violation for the contact with F3?

Why would you have a running lane violation? The runner did not interfere with a throw or catch at 1st base. In fact, as described, F3 was not fielding a batted ball or recieving a thow at 1st base, and impeded the runners progress to 1st base. You could very possibly have obstruction on F3.

My underlying question was on weather a obs could be called on F3 because the runner was not in the running lane and F3 was just standing in the field.

Running lane only applies to the runner interfering with a throw to 1st base or the ability of the defense to catch the ball at 1st. There is no requirement for the runner to run in the lane, they are simply protected from being called out for interference if they are in the lane.

Not to nitpik here, but only the latter applies. The rule is based solely on the availability and ability for a defender to receive the throw at 1B.

Yes, OBS could be called on F3. Running lane is completely irrelevant here.

Of course OBS is a very real possibility here. (See the previous posts regarding the running lane.)