How to attach a potentiometer to a servo motor shaft

I got a chance to go out and measure the control arm. It measures 12 inches.

If i attach the motor at the same point thst will illiminate issues converting it to linear motion. Although it means a bigger motor is needed.

15 lbf * 1' means 15 torque? That would mean just about 20 nm of torque?

If i mount the motor higger and just deal with the uneven motion i can cut that in half. Thats still a good size motor.