Just a few minutes ago, we released obRSS 1.9 which improved SEF URL prefix for Feeds.

In the case of making your Feed SEF URL prefix with .rss, .xml or .json, you need to slightly modify your .htaccess file (you can find it at JOOMLA_FOLDER/.htaccess). Here is the instruction to modify it:

Find above line (if you didn't make any change for the file, it is probably the line #68):

RewriteCond %{REQUEST_URI} /component/|(/[^.]*|\.(php|html?|feed|pdf|vcf|raw))$ [NC]

Replace it by:

RewriteCond %{REQUEST_URI} /component/|(/[^.]*|\.(php|html?|feed|rss|atom|json|pdf|vcf|raw))$ [NC]

If you want to add more URL prefix, just follow that format to add more, whatever you want.

For example, for newsml URL prefix, you can add it like this:

RewriteCond %{REQUEST_URI} /component/|(/[^.]*|\.(php|html?|feed|rss|atom|json|newsml|pdf|vcf|raw))$ [NC]