There was a thread on this topic just a couple of weeks ago. I was told by a Chabad rabbi that because we are saying “v’zot ha Torah”, meaning “this is the Torah” and we are pointing at it with our pinky. I have heard other explanations as well – one was that the pinky is the smallest finger and it means that perhaps we learned even a little bit of Torah on this day. I am sure that there are other explanations as well.
I assume this is when the Torah is held up after the reading? I don’t konw the term ‘Hagboh’, but I think I read that once on here. To kiss your pink indicates that you are smaller than Torah but that you love your own soul just as well. But that said, we usually lift our tzitzis in the air and then kiss the tzitzi afterwards. This indicates that we love our heritage.
Its probably like minyangal says: “zeh” is mashmah being moreh b’etzbah, like by kidush levanah, the menorah and machatzis hashekel. So when we say “vzos haTorah” we are moreh b’etzbah.