How do AP readers record score of each response?

From what I've seen from old AP tests that teachers have access to, there's a grading rubric sheet of sorts that doesn't have all the instructions on it (that's another page), but rather that has spaces for the amount of multiple choice correct and then spaces for the amount of points on each free-response / essay question, then a space for the total amount of points and a scale for converting the raw score to the scaled 1-5 score. My guess would be that they paper clip this to your test materials and just keep them together when sending them around to be graded.

No, they bubble in score on a scantron and it is all calculated by a computer.