findByPk() with

I'm using CDbCriteria->with to get additional data from other tables:

$criteria = new CDbCriteria;
$criteria->with = array('userData', 'orderedProducts');
return new CActiveDataProvider('AR_Orders', array(
	'criteria'=>$criteria,
	...
	),
));

It's not clear to me, how to use 'with' when loading data via findByPk:

$order = AR_Orders::model()->findByPk($id, '', ???what to write here???));

Thanks!