<script src="https://js.recurly.com/v4/recurly.js"></script>
<link href="https://js.recurly.com/v4/recurly.css" rel="stylesheet" type="text/css"> 

<form>
  <input type="text" data-recurly="first_name">
  <input type="text" data-recurly="last_name">
  <div data-recurly="card"></div>
  <input type="hidden" name="recurly-token" data-recurly="token">
  <button>submit</button>
</form>