Tom:
When adding the reference, use the Browse option to find EXTRACOM.dll (not EXTRACOM.tlb) in Reflection's installation directory. Note that if you're using the latest Reflection, adding the reference will require using ".NET Framework 4" as your Target. You'll want to change your project's Target first and then add the reference (if you add the reference and then change the Target, things can sometimes get confused).
Good luck!