This work addresses geometric considerations relevant to the accuracy of depth profiling by reflection elastic recoil detection analysis, which becomes an issue when many samples are compared over time or a single sample is repeatedly analyzed following a sequence of processing steps. In such cases, accurate and reproducible geometric alignment and incident beam energy calibration must be performed over time, and are addressed here. Our analysis and experiments show that geometric deviations in the sample tilt angle and incident particle beam steering, as well as deviations from the sample eucentric position, can result in significant errors in depth profiling. As a result, a recommended degree of accuracy is stated for each of these geometric components; techniques are presented to attain this accuracy, or better. The most notable of these techniques is a laser alignment of the sample tilt angle, which has a reproducible accuracy of 0.04°.