// this is for the edit profile; for register please use the following filter: extraRegistrationField
add_filter( 'extraEditProfileFilter', 'add_horoscope' );
function add_horoscope(){
    $extra_content = '';

    if ( 'POST' == $_SERVER['REQUEST_METHOD'] && !empty( $_POST['action'] ) && $_POST['action'] == 'update-user' ){
        if isset( $_POST['date'] )
            $date = $_POST['date'];
    }

    $extra_content .= '
        <p class="form-date">
            <label for="date">Date</label>
            <input class="text-input" name="date" type="text" id="date" value="'. $date .'" />
            <span class="wppb-description-delimiter">Enter your birthdate</span>
        </p><!-- .form-date -->';


    if ( isset( $date ) )
        $chinese_zodiac_code_or_string = ''; // add yours here

    $extra_content .= $chinese_zodiac_code_or_string;

    return $extra_content;
}