I see both Feed Url contain class: wp-caption. How about adding following styles in HTML Header? if it could fix the problem, we could implement it in codeit works good, check the code here: http://jsfiddle.net/5am30c5a/2/
I removed the links around the <img /> tags using jQuery and added default appyet CSS code, all images are resized correctly.
.wp-caption{width: auto !important; height: auto !important; max-width: 100%; padding:0px !important; margin-left:0px !important; margin-right:0px !important; margin-top:0px !important; margin-bottom:0px !important }