WooCommerce, adding add_to_cart on shop page for external product

Hi,

I have a WooCommerce installation with almost only external products. On the shop page I have a short description and then only the Read More button. What we would like is a read more button AND an add-to-cart button that redirects inmediately to the external shop. I try to find how to add the code to accomplish that but can’t find it. Hope someone can help me out here