<select class="selectpicker" bootstrap-selectpicker data-ng-model="modelValue" multiple="" data-actions-box="true">
 <option>Mustard</option>
 <option>Ketchup</option>
 <option>Relish</option>
</select>

app.directive('bootstrapSelectpicker'), function($compile, $parse){
var bootDirective = {
    restrict : 'A',
    link: function(scope, element, attr){
        $('.selectpicker').selectpicker();
    }
};
   return bootDirective;
});