/usr/lib/x86_64-linux-gnu/librdf.so is in librdf0-dev 1.0.17-1.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/librdf.so.0.0.0
/usr/lib/x86_64-linux-gnu/librdf.so.0.0.0