I had built a site with RSD many years ago, but I was trying to figure out what Framework I should use.

There are some general notes about the choice of frameworks at
https://www.coffeecup.com/forums/site-d … post302948

To check which framework was used to build the website mentioned, I would look at the source code for one of its pages. In the head code there's likely to be something like one of the following.

<link rel="stylesheet" href="css/vanillacss.min.css">
<link rel="stylesheet" href="css/bootstrap4.min.css">
<link rel="stylesheet" href="css/foundation.min.css">
<link rel="stylesheet" href="css/materialize.min.css">

Vanilla is Frameworkless, the others need no interpretation. Seeing the source code in a browser is often by keying Ctrl+u for Windows users. I guess it's something similar for those using the MacOS

Frank