hi nnelson97,
After lock the remote desktop, you can choose the "sign-in options" button and use the smart card login. This is not related with protocol which one you selected and you can use RDP, Blast or PCOIP.
Below is my screen record to show how the smart card work under session locked scenario. It should be work for customer.
What's your problem in detail?
1. can not see the "sign-in options" button on your login page?
or
2. there has a additional other issue shown once you choose to use smart card to unlock it?