Why do people raise their pinkies during hagbah? what is the source for this practise?

In the Shulchan Aruch Orach Chaim 134:2 makes no mention of this minhag, neither does the Mishna brura. I have not found any mention of this minhag either in Taami minhagim or in Yalkut Yosef or Tefila Kehilchata. The mitzva is to see the letters, not point to them. It is good if one can actually read the letters for accoridng to the kabbala this will bring "great light " to the reader. Mishna Brura 134:11.