Apparatus and method for reference point teaching for an articulated member, such as a robotic arm. An end effector is moved to form a witness mark on a medium at a target location. An updated reference point for the end effector is generated in relation to a detected coordinate of the witness mark. The end effector preferably supports a gage with a tapered probe, and a distal end of the probe contactingly engages the medium to form the witness mark. A vision system preferably detects the position of the witness mark after retraction of the end effector away from the mark. The medium preferably comprises paper, and the witness mark preferably comprises a hole punched therethrough. Alternatively, the medium comprises pressure sensitive paper and the mark is formed by the application of pressure thereto. The gage can comprise two probes that make two spaced apart witness marks, as desired.