Reference edition:

Rhetores Latini Minores, ex codicibus maximam partem primum adhibitis emendabat Carolus Halm, Lipsiae 1863, 313-352 (Bibliotheca Scriptorum Graecorum et Romanorum Teubneriana).

A new edition is being prepared by R. Jakobi (2017).

The title Institutiones oratoriae, with its echo of the name of Quintilian’s magisterial work, promises far more than Sulpicius delivers. He says something about most aspects of rhetoric, but devotes far more attention to the status-system than to anything else. [M. Winterbottom].