After put in a "fix" for not been able to find the "export" file, PiSharpGpio ran on my Mac. However, towards the end it threw a file not found exception in the LibGpio.UnExport( BraodcomPinNumber pinNumber) method.
The file /tmp/RasPiGpioTest/unexport does not exist and I can't seem to find where it should be created.
The file must exist when using FileMode.Open in the FileStream constructor.