Does the HTML button work? How do you put turn it on?

FYI I just tried putting the above code into the "Insert HTML" box and it did not work...

James, to add iframe code to the post go to Admin Area > Settings > User Settings > Content Input tab and ensure you did not disabled the "Disable custom HTML" check box.
Then create a post, click the "HTML" button and paste the code by following these instructions: https://developers.soundcloud.com/blog/html5-widget-api .
We've checked and everything is working on our Demo (see screenshot).

Do you have to add the normal soundcloud embed code as well as the script that it says on https://developers.soundcloud.com/blog/html5-widget-api ? This;

<script src="https://w.soundcloud.com/player/api.js"type="text/javascript"></script>

On Geek.Zone the HTML button produces this;

What can I do to fix it?

James, this script tag <script src="https://w.soundcloud.com/player/api.js"type="text/javascript"></script>  should be inserted in Admin Area > Settings > Main Settings > Page Settings section. Insert  it into the "Custom head code" field.

Tried that, doesn't work. What is going wrong?

James, please see at screenshots bellow:




Here the iframe code we have added:

<iframe id="sc-widget" width="100%" height="166" scrolling="no" frameborder="no" src="https://w.soundcloud.com/...&amp;visual=true"></iframe>

I think this could be related to the Insert HTML popup being blank. I will go through your suggestions on that issue then come back to this one