contact.cshtml

@using System.Configuration

<script type="text/javascript" src="http://www.google.com/recaptcha/api/js/recaptcha_ajax.js"></script>
<script type="text/javascript">
    $(document).ready(function () {
        captcha();
    });

    function captcha() {
        Recaptcha.create("@(ConfigurationManager.AppSettings["recaptchaPublicKey"])", "captcha",
        {
             theme: "red", callback: Recaptcha.focus_response_field
        });
    }
</script>
<div id="target">
    @Html.Partial("Form")
</div>