Can a URL be enclosed in a frame?

Hi,

I am trying to embed a URL into a blog post but I want to constrain it in a frame or box. The URL works fine when I use %URL% but when I try to enclose it in <iframe /iframe> the frame shows up but the content is missing. The content is an html interactive network graph. Is there a way to do this?

I’m very new at this so apologise if it is something obvious that I have missed.

Thank you for such a useful plugin.
Sara