You havn't stated that you are a registered dealer under CST Act. If you are a registered dealer and if you hv obtained "C" form from the buyer then it is 4%, provided the product undergo for re sale in Hydrabad.
In case the buyer is purchasing the product for his personal use not for resale then the rates are different.
If the buyer happens to be a public charitable trust exempted from paying sales tax by the AP Government then there is no tax is involved.