Set up a new blank page in a Sandvox site

Make sure you have the option Load data from the Internet checked (under preferences) so that you'll see your changes immediately.

With the above page selected, insert an external page object

  1. Objects
  2. External Page
With the above page selected, insert an external page object

This gives you an empty blue frame, make sure it's selected by clicking once

Resize the frame to suit. By dragging, I could only get 640 px wide.

After showing the inspector,

  1. Click on the Metrics ruler (5th box)
  2. Enter the desired size.

If it changes during editing, redo it.

There are a couple ways to add a URL to this box

You can drag it directly in from a web page (into the frame), or

  1. With the inspector selected, click on the Object link (last tab)
  2. Paste in the URL of the external page

You can do this three times for your site.