You need to underline, at least. Annotating is a good idea, for organizational purposes. IMO the physical, bodily connection helps to maintain focus and concentration. At the minimum, your pencil should be in your hand, and you should be using the tip to trace beneath the words as you read, to prevent regression and fixation.
Also, try not to be so conscious of and deliberate in how fast you are reading. Your diverting your attention when you do, you are split between adjusting your speed and the actual act of reading. You don't need to be a speed-reader -0 on RC. When you read well, you don't generally NEED to return to the passage to select the right answer.
For reference, I'm usually no more than -2 on RC, but often -1 or -0. Although, went -3 on the September test.