Finally i got it working, here is my code

start: function() {

            var self = this;
            this.field_manager.has_been_loaded.done(function() {
                $('#rateit').rateit({
                    value: 0,
                    resetable: false
                });
                self.field_manager.on("change:actual_mode", self, self.check_actual_mode);
                self.check_actual_mode();
            });

 },
 
 check_actual_mode: function(source, options) {
    var self = this;
    if(self.field_manager.get("actual_mode")=='view'){
        $('#rateit').rateit('readonly',true);
    }
    else {
        $('#rateit').rateit('readonly',false);
    }
}