You can do the following guide.

1. Go to cPanel -> File Manager -> public_html -> {publish_folder}/

        Sample::

domainname.com, should be in public_html

        domainname.com/myname, should be public_html/myname (if your public_html doesn’t have this folder, just feel free to create it)

2. Create a new file under the folder in number 1. with the name such as; feed.html

and insert your RSS FEED code to the file.

3. Back to RVsitebuilder -> Step 3 -> Page Editor -> Switch to "Source" view, and insert code:

 <object type="text/html" data="feed.html" width="100%"></object>

*feed.html is the file you created in number 2.

4. Republish again.