add a new field in a view that uses a teaser view mode fomat
Seeing that you are using Display Suite, you should add the field via Display Suite as node.tpl.php is no longer being used. Display Suite has 4 Custom fields that you can add via the interface. You should look into the 'preprocess field'.

You need to define a preprocess field in Display Suite



and the machine name of the preprocess field 



should correspond with the name of the field that you provide in your preprocess_node function:

function MYMODULE_preprocess_node(&amp;$vars) {
  $vars['my_new_field'] = "some html or rendered field";
}


You are of course not limited to creating your field value in the preprocess_node function, you could just hand the value over like this:

function custom_preprocess_node(&amp;$vars) {
  $vars['my_new_field'] = drupal_render($vars['content']['get_reward_link']);
}


The only limitation (AFAIK) is that you have to render the field before you let Display 
Suite pick it up.

Once you have defined your preprocess field like this, Display Suite will make it available in the manage display tab for the node type.

Also look at Theming with Display Suite and Preprocess Functions