KHOBAR, Saudi Arabia, March 1 (Reuters) - Saudi Kayan Petrochemical Co said on Sunday that its president Mazyad al-Khaldi had resigned for personal reasons. The company, an affiliate of Saudi Basic Industries Corp (SABIC), said in a statement on the bourse website that Khaldi's resignation would take effect from March 31. It added that it would an**unce at a later stage the appointment of a new president. Last month, SABIC named Yousef al-Benyan as its own acting chief executive after Mohamed al-Mady assumed a**ther post at a top state corporation. ...