Failover clustering is supported only for the report server database; you cannot run the Report Server service as part of a failover cluster.
To host a report server database on a SQL Server failover cluster, the cluster must already be installed and configured. You can then select the failover cluster as the server name when you create the report server database in the Database Setup page of the Reporting Services Configuration tool.
Although the Report Server service cannot participate in a failover cluster, you can install Reporting Services on a computer that has a SQL Server failover cluster installed. The report server runs independently of the failover cluster. If you install a report server on a computer that is part of a SQL Server failover instance, you are not required to use the failover cluster for the report server database; you can use a different SQL Server instance to host the database.
Hope this helps!