An example WordPress plugin that hooks into the SlickQuiz WordPress plugin. Thanks to @phh for his contribution and example from which this is modified. https://github.com/jewlofthelotus/SlickQuiz-WordPress/pull/37

CustomSlickQuizFilters.phtml

class CustomSlickQuizFilters {

    function __construct()
    {
        add_filter( 'slickquiz_admin_options', array( &$this, 'custom_admin_options' ) );
        add_filter( 'slickquiz_after_options', array( &$this, 'custom_after_options' ) );
        add_filter( 'slickquiz_after_result', array( &$this, 'custom_after_result' ) );
    }

    function custom_admin_options( $options )
    {
        $options['read_more_links'] = '';
        return $options;
    }

    function custom_after_options( $obj )
    { ?>
        <h3 class="title">Result Options</h3>
        <table class="form-table">
            <tbody>
                <tr valign="top">
                    <th scope="row">
                        <label for="slickQuizOptions[read_more_links]">Read more links:</label>
                    </th>
                    <td>
                        <textarea name="slickQuizOptions[read_more_links]"><?php _e( apply_filters( 'format_to_edit', $obj->get_admin_option( 'read_more_links' ) ) ); ?></textarea>
                    </td>
                </tr>
            </tbody>
        </table>
        <?php
    }

    function custom_after_result( $obj )
    {
        $out  = '<div class="read_more_links">';
        $out .= $obj->get_admin_option( 'read_more_links' );
        $out .= '</div>';
        return $out;
    }

}

$custom_sq_filters = new CustomSlickQuizFilters;