protected function _prepareLayout() {
// Load Wysiwyg on demand and Prepare layout
        if (Mage::getSingleton('cms/wysiwyg_config')->isEnabled()) {
            $this->getLayout()->getBlock('head')->setCanLoadTinyMce(true);
        }
        return parent::_prepareLayout();
}

$fieldset->addField('description', 'editor', array(
            'name' => 'description',
            'label' => Mage::helper('recipe')->__('Description'),
            'title' => Mage::helper('recipe')->__('Description'),
            'style' => 'width:700px; height:200px;',
            'wysiwyg' => true,
            'required' => true,
));