Correct radio syntax (not checkbox)

I have this syntax to provde a series of checkboxes. This works fine, however no matter what syntax I use to get radios I get nothing, just a blank space.

I've tried 'type' => 'radio', and tried 'type' => 'radiogroup',

this what I'm using now.

array(
'type' => 'checkbox',
"holder" => "div",
"class" => "",
"heading" => __("Choose your cheese topping", 'rbm_menu_item'),
'param_name' => 'cheesbox',
'value' => array( 'Cheddar'=>'Chedder', 'Gouda'=>' Gouda', 'Bleu'=>' Bleu'),
"description" => __("<br /><hr class='gduo'>", 'rbm_menu_item')
),

any ideas? Is there a different way to get radios instead of checkboxes?