Content of data-ref depends on the value or static? if it's not static, impossible with using $form->radioButtonList, do this with old-school method. Otherwise it's simple
<?php
echo $form->radioButtonList(
$model,'refinement_id',
CHtml::listData($refinements, 'id', 'label'),
array('separator'=>'</li><li>', 'container' => '', 'data-ref'=>'fshafh'));
?>