How to add Reflection for UNIX and OpenVMS reference to C#?

I am trying to add a reference to Reflection for UNIX and OpenVMS to my C# project but get the following error

A reference to 'Reflection for UNIX and OpenVMS' could not be added

Does this mean I do not have that library ? Why would it show up then ? Can I download it and then reference ? I could not find the libraries on their website .