Using Radio Buttons in WordPress Theme Options

I’m completely stuck.

I’ve been working on a theme that offers 5 different layouts and 3 different skins. In the theme options, I originally was using checkboxes to choose the skin and layout, but was asked (by ThemeForest) to change them to radio buttons. At first, I thought, no problem. Now I’m clueless.

In the header, an example of a layout + skin option was written like this:

<!-- Content Alt (Layout 2)-->
<?php if (( $mp_content_alt == 'true' ) && ( $mp_skin1 == 'true') ){ ?>
<link rel="stylesheet" href="<?php bloginfo('template_url'); ?>/_styles/skins/l2_coolblue.css" type="text/css" media="screen,projection" />

<?php } elseif (( $mp_content_alt == 'true' ) && ( $mp_skin2 == 'true') ){ ?>
<link rel="stylesheet" href="<?php bloginfo('template_url'); ?>/_styles/skins/l2_justminimal.css" type="text/css" media="screen,projection" />

<?php } elseif (( $mp_content_alt == 'true' ) && ( $mp_skin3 == 'true') ){ ?>
<link rel="stylesheet" href="<?php bloginfo('template_url'); ?>/_styles/l2.css"  type="text/css" media="screen,projection" />

<?php } ?>

In the functions.php I set up the radio options like this:

$shortname = "mp";
$layout = array("1" => "Original", "2" => "Original + Left Sidebar", "3" => "Wider  Images + Right Sidebar", "4" => "Large Images + No Text", "5" => "Smaller Images Gallery");
$skins = array("1" => "Original", "2" => "Cool Blue", "3" => "Just Minimal");

array( "name" => "Choose A Skin",
"desc" => "",
"id" => $shortname."_skins",
"type" => "radio",
"options" => $skins,
"std" => ""),

array( "name" => "Layout Options",
    "desc" => "Choose Your Layout",
    "id" => $shortname."_layouts",
    "type" => "radio",
    "options" => $layout,
    "std" => ""),

I’m struggling to understand how to call the different radio options? I tried this:

<!-- Content (Layout 1)-->
<?php if ((checked( isset( $mp_layouts['1'] ) ) ) && (checked( isset( $mp_skins['2'] ) ) ) ){ ?>
<link rel="stylesheet" href="<?php bloginfo('template_url'); ?>/_styles/skins/l1_coolblue.css" type="text/css" media="screen,projection" />

<?php } elseif ((checked( isset( $mp_layouts['1'] ) ) ) && (checked( isset(   $mp_skins['3'] ) ) ) ){ ?>
<link rel="stylesheet" href="<?php bloginfo('template_url'); ?>/_styles/skins /l1_justminimal.css" type="text/css" media="screen,projection" />

<?php } elseif ( (checked( isset( $mp_layouts['1'] ) ) ) && (checked( isset( $mp_skins['1'] ) ) ) ){ ?>
<link rel="stylesheet" href="<?php bloginfo('template_url'); ?>/style.css" type="text/css" media="screen,projection" />

<?php } ?>

But that didn’t work.

Any suggestions?

Thanks very much!