Hi David !...
rdesktop does not support NLA which is a feature introduced with recent versions of Windows.
In addition, is not clear to me that it wil support this feature in a near future.
This means that unless NLA is turned off, the number of Windows machines to which is not possible to connect using PAC is increasing ;-)
So, it would be great if you add support for freerdp :-)
Once more thanks for your work & support !