DOHA: Qatar's top international referee Abdulrahman Al-Jassim will leave on Thursday for China to feature in the AFC Under-23 Asian Cup, scheduled to start on January 9.       Al-Jassim's choice to participate in the Asian Championship is the culmination of the excellent levels he offers in various tournaments. This is not the first time Al-Jassim has been chosen for a top event.       His last overseas participation was  refereeing at the Club World Championship in Abu Dhabi.       Abdulrahman Al-Jassim is one of the top referees in Qatar and has run many important finals in Qatar.