title: Show Magento attribute as a selectable option on frontend
body: <p>In my Magento shop I want customers to select the size of the product which they wish to order.
  I've created a custom attribute <code>ringsize</code> with options ranging from 15 to 22.
  I see the attribute dropdown appear in the backend when adding a new product, however, I don't select a value here, since that is up to the visitor on the frontend.</p>
  
  <p>Now, when I visit my product detail page on the frontend I don't see a dropdown where a visitor can select the site of the product. How do I enable that? Should it be done in the template or is this something Magento would provide out of the box?</p>