Where i can edit RSS Feed layout for Instant Article?.

Hi,

Currently my instant article got an error:

"General Warnings: Default Audience Network Ad Template is Being Used: No custom Ad Template was specified, therefore the article is using the Default Audience Network Template, which allows for automatic ad placement. You can always set up your ad template or disable automatic ad placement to clear this warning. Refer to Ads & Analytics in the Instant Articles documentation for more information."

There got some bug on rss feed generator for instant article. I need to know where the php files which is i can modify the rss feed for instant article layout.

Thanks.