This is a fairly trivial exercise with help from the Read More Control module.

This example provides a read more link on a user listing generated using the Views module.

Define a view mode

Site builders should check out the Entity view modes module.

Programmers can simply define additional view modes using hook_entity_info_alter().

/**
 * Implements hook_entity_info_alter().
 */
function MODULE_entity_info_alter(&$entity_info) {
  $entity_info['user']['view modes']['teaser'] = array(
    'label' => t('Teaser'),
    'custom settings' => TRUE,
  );
}

Like any new Drupal hook, a cache flush is required.

Visit the user display settings

Visit the user display settings page:

Administration » Configuration » People » Account settings » Manage Display

Under custom display settings, check the newly defined view mode and save.

Enable the Read More link on the custom view mode

Select the newly created tab, Teaser in this case, and select your desired configuration and SAVE.

There is a catch 22 to this module. You must save the settings (even if they are not changed) before they start working. This was deliberately done to prevent Read More links appearing all over the place.

The only exclusion to this rule is the node entities teaser view mode that is enabled and inherits the global settings by default.

Create a listing

Simply create a user listing using the Views module and select a content listing of type Teaser.

Of course you would probably want one or more fields on the user entity to compare, although not required if you configure the Read more link to always appear.