It seems index hint option was removed from database tuning tab in AX Server Configuration Utility for Dynamics AX 2012 R2. I've seen this in (former) CU1 and CU6.

How do you test it?  The following code which tries to specify the index hint, won't work...

EDIT: When enabling this feature, the form under procurement and sourcing --> categories --> Procurement categories will issue the following error:

SQL error description: [Microsoft][SQL Server Native Client 10.0][SQL Server]Query processor could not produce a query plan because of the hints defined in this query. Resubmit the query without specifying any hints and without using SET FORCEPLAN.

This error is solved if you don't use the index hint