The PDF version of How to Render is not a "hack" to get out of buying the book; it is a superior reference tool for the digital age. It serves as a technical manual for lighting that belongs on the desktop of every 3D modeler (for texture baking) and every concept artist (for material callouts).
Introduction: Beyond Line Art
The PDF is only useful if you follow the "Do It Alongside" method. Robertson explicitly states in the intro (page 12) that rendering is a motor skill, not an intellectual one. You cannot learn rendering by scrolling; you must trace his gradients, copy his chrome spheres, and fail at his "reflective pavement" exercises. How To Render Scott Robertson Pdf