Deb,
The attachment covers standardization of milk by adding powder, which should not be confused with the question from Aris. This information is actually somewhat outdated. What we do now is strip out the cream, pasteurize that separately, then put it back in to the milk stream at the desired PF ratio. If you have a UF plant you can tweak further by adding retentate (protein concentrate) or, if you have equipment to handle the slurry, adding milk protein concentrate (MPC).
Note that on page 2 it talks about low heat powders, this is because normally produced powders are hot enough to denature the protein and you can't get it back into solution. Also note all the exceptions and conditions around powder addition in this cases.