The following code can be used to add embedded rooms in Drupal:
<style>
.drupalchat-embed-chatroom-content {height: 550px !important;}
</style>
<script type="text/javascript">
Drupal.settings.drupalchat.embed = "1";
Drupal.settings.drupalchat.ur_hy = "1";
Drupal.settings.drupalchat.embed_msg = 'Type your message here. Press Enter to send.';
Drupal.settings.drupalchat.embed_online_user_text = 'Online Users';
</script>
<div id="drupalchat-embed-chatroom-0" class="drupalchat-embed-chatroom-container"></div>
Note that you should be using a premium plan in order to be able to use embed chatroom.
The embed chat can further be customised. Please refer to the following articles: