The back top part of your head is about the spot where the hair falls in a circular pattern on most folks heads. Just touch that part of the head and notice the sensation that stays there for a while. The buzzy feeling is nice, no need to force it, just focusing toward that point helps the photoreading experience.
Just do the steps of photoreading with a sense of relaxed curiosity. If you find it hard or feel you have to bring about certain feelings or sensations to make it work you risk building barriers. With a sense of relaxed curiosity you remain free to discover the what and how each step works for you. 'Trying' to get that dizzy buzzy feeling may be more effort than you really require. You might just need to take a deep breath and focus on taking deep breaths while turning the pages rather than generate a particular sensation in your head.
'Trying' implies effort and not expecting a positive result which is the reason for my comments above. If you have a method of producing that feeling, it comes to you without effort and you enjoy it. Then by all means keep doing it. If the effort of generating that produces a super headache the following day... relax 
Alex