How to add invited users to Multiple Roles at a time

Hi Everyone,
I have one query myside,Please help me anyone.I Installed "INVITE" module In my local.I created the roles and set permissions also.when i navigate to Invite settings Like "Home » Administration » Configuration » People",here display the Role settings, the Target roles are displying like dropdown,now select the only one Role at a time,But i want to select the multiple roles. Please give me any suggestions.

Thanks
SMK