Add an html snippet some within body of the theme using preprocess
You should add hook_node_view() into your module. See the given example on how to add HTML markup.

function mymodule_node_view($node, $view_mode, $langcode) {
  $node-&gt;content['my_additional_field'] = array(
    '#markup' =&gt; $additional_field, 
    '#weight' =&gt; 10, 
    '#theme' =&gt; 'mymodule_my_additional_field',
  );
}