How to add external element to page:

1) Under "Site" menu on left side of Builder

2) Select "Pages"

3) Double click the page you wish to add Element to

4) Select "Elements" tab on the right side of Builder

5) Click "+" icon at the bottom of Builder

6) Hover over "Content" and select "External"

7) Here you can add the Url to the page you want to have viewed and adjust the window size.

Once changes are complete make sure to publish.