Generally Zaidis dont raise the finger in the tashahhud. This is because it negates the Prophet's (sawas) command: ((Be calm in the prayer)). Those reports that mention the raising of the finger are disputed even amongst the scholars of the Generality. That being said, there is a hadith in one of our books of hadith Amaali Abu Talib narrated on the authority of Ja'far as-Saadiq (as) in which the Prophet is reported to have said: ((Indicating with the finger is a testimony to Allah's Sublimity (musabbiha)...)) Allah knows best regarding its authenticity. It is for this reason that some of our scholars permit raising the finger in tashahhud at the point that one says Laa ilaha ila Allah--similar to what the Hanifis do.