all four KING FM channels are available on your SoundBridge (and have been for quite some time). You will find them as follows:
KING 98.1 FM Seattle, WA (MP3 48k) is Radio Roku ID # 768
KING 98.1 FM Seattle, WA (WMA 40k) is Radio Roku ID # 43858
KING 98.1 HD2 Seattle, WA (aka "Arts Channel") is Radio Roku ID # 42701
KING FM Evergreen Channel is Radio Roku ID # 42876
KING FM Seattle Opera Channel is Radio Roku ID # 42700
As Alan suggested, reading http://forums.rokulabs.com/viewtopic.php?t=16320
is a good idea, anyway.