This plugin modifies RSS feeds and ATOM feeds as you want.
This plugin modifies RSS feeds and ATOM feeds as you want. in plugins "feedfile" directory all the files are listed
Just now it's show your feed image (post image), if you want you modify you can easily modify.
Putting the following templates into the current theme folder, then you can use the customized feed templates instead of the default ones.
Note: When these feed templates are not in the current theme folder, WordPress's default feed templates will be used.