Multiple projects need to use 1 SNK file

I'm using Visual Studio 2008 and I have a solution which contains multiple projects. I have 1 snk to sign my assemblies and this lives in a solution folder.

I've linked the snk to each of my projects but now when I attempt to sign my project with that linked snk I can't find the snk file with the file dialog.

Have I missed a step here?

Solution
   > Solution Folder
       MyKey.snk
   > Project X
       > _LinkedFiles
           MyKey.snk (physical file doesn't appear here but shows in VS)
       > ...