The librdkafka.redist NuGet package contains librdkafka libraries compiled for the following platforms, distros and features.

The disparity in build-time features is a compromise between NuGet package size (fewer libraries) and required system dependencies (e.g., Cyrus SASL / Kerberos). If GSSAPI support is required on a platform for where there is no corresponding library with GSSAPI support you will need to install librdkafka through other means and specify the installed library path using Library.Load (API docs).

See librdkafka.redist Wiki entry