No, you definitely should not. When you hold or touch an antenna with exposed metal surfaces, your body distorts the signal and alters the antenna’s performance.
With a Yagi antenna, weBoost recommends that you temporarily mount the antenna so you can point it in various directions while looking for the source of the strongest signal.
It is important that you are not in contact with the antenna when taking a signal strength reading. Contacting the antenna can produce inaccurate readings, which can lead to less than optimal antenna positioning and degrade your booster system's performance.