The functionality to export to PDF is only built in directly to the Qlik Sense client, meaning not when embedded into another site or portal. If you require this in an iframe, then this functionality (in my view) will need to be added manually via code within the HTML code, if at all possible.
I hope this answers your question. If so, please mark this answer as helpful and as answered
I know this is an old thread, but for those that are using qlik sense > v2
With Qlik sense > 2.x, you can export when you right qlik on your embedded qlik app, but you need to expose your app, like so:
<iframe id="masterlist-iframe" src="<qlik.host.url>/sense/app/<qlik app id>/sheet/<qlik sheet id>/state/analysis/options/clearselections" style="border:none; height: 100%; width: 100%;"></iframe>
Then you can right click on your chart/table --> ... --> export.