You'll want to look at the "object" tag, with the data attribute set to your embedded page, because iframe is deprecated anyway. As for the sizing/zooming issue... you'll just have to try it. I haven't had to do anything like that, so I'd hesitate to make a guess at how that will work.
I think you can use render partial method instead of IFRAME http://api.rubyonrails.org/classes/ActionView/Partials.html
good luck =)
I am building an admin interface where users can adjust the header/footer, content, etc... for their website. I want to display their site as they make changes. When displaying it I need to display it at like 50% normal size. I thought about using an IFRAME with the zoom style to shrink the page but there are browser compatibility issues with zoom and thought there had to be a better way. Any suggestions would be welcomed.