Problem: When you run your feed through FeedValidator you receive an error similar to:

Your feed appears to be encoded as “utf-8”, but your server is reporting “US-ASCII”

Answer: What this means is that your server is configured to automatically send out your .php files marked as “US-ASCII” text.  This conflicts with what you have set as the encoding in your feed.

If you are running in an Apache-based webserver, you can tell your server to deliver all of your .php files (which would include everything served through ExpressionEngine) marked as a particular character set/encoding.

First, you need a .htaccess file in your main site directory.  Inside that file, place this, where you specify the character set you want to use: