A quick test using the Sandcastle Help File Builder showed that in the generated documentation, the link <seealso cref="IFoo.Bar()"/>points to a method in the interface and <seealso cref="Bar()"/>points to a method in the class. The documentation for an explicitly implemented method is inherited from the interface, so in any case, you should actually point to the interface method.
: ReSharper <seealso cref="FooClass.IFoo.Bar()"/> <seealso cref="IFoo.Bar()"/>, , .