/usr/include/GNUstep/Frameworks/RSSKit.framework/Headers is in librsskit-dev 0.4-1build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/include/GNUstep/Frameworks/RSSKit.framework/Versions/0d
/usr/include/GNUstep/Frameworks/RSSKit.framework/Versions/0d