Try [Advanced Custom Fields][1] and simply add a WYSIWYG editor.

Step 1
![Step 1][2]

Et Voila!
![And Voila!][3]

Displaying the input on the front-end

    <?php
      /* Put the attachment ID in place of 999 */
      // Display
      the_field('yea', 999);
      // In case you need to don't want to display it right away
      get_field('yea', 999);
    ?>


  [1]: http://wordpress.org/plugins/advanced-custom-fields/
  [2]: https://i.sstatic.net/MrEpl.png
  [3]: https://i.sstatic.net/xVwvA.png