Can the FORCESEEK query hint be used on tables being queried against on a linked server? (I.e. as part of a distributed query)
You CANNOT use FROCESCAN or FORCESEEK on remote data sources.

Reference: Hints (Transact-SQL) - Table

The FORCESCAN hint has the following restrictions:


  The hint cannot be specified for a remote data source.


When using the FORCESEEK hint (with or without index parameters), consider the following guidelines:


  The hint cannot be specified for a remote data source. Error 7377 is
  returned when FORCESEEK is specified with an index hint and error 8180
  is returned when FORCESEEK is used without an index hint.