CONFIG_SH_RSK is not available for thedefaultarchitecture x86.
Result is shown for architecture sh

Renesas Starter Kit

configname: CONFIG_SH_RSK

Linux Kernel Configuration
└─>Board support
└─>Renesas Starter Kit
In linux kernel since version 2.6.29 (release Date: 2009-03-23)  
Select this option if configuring for any of the RSK+ MCU
evaluation platforms.