The Kaf Ha'chayim (by Rabbi Yaakob Hayim Sofer) in siman 22: S"K 9, cites a view requiring one to hold the Tallit in his right hand as he recites the Beracha before donning the Tallit. Just as one who recites a Beracha before eating should hold the food in his right hand, so should one hold the Tallit in his right hand while reciting the Beracha of "Le'hit'atef Be'tzitzit." The Kaf Ha'chayim records that this was the practice in the renowned Yeshivat Bet-El in Jerusalem. A number of Rabbis in the community followed this practice, as well, including Chacham Avraham Zafrani A"H.
However, Chacham David Yosef (son of Chacham Ovadia Yosef), in his work Halacha Berura, Helek 1, page 142, S"K 16, notes that this custom does not appear in any other major Halachic works, and therefore those who are accustomed to hold the Tallit with both hands while reciting the Beracha have on what to rely and need not change their practice.
