According to this completely unscientific poll, 43% of RK readers are from Northern Virginia, which of course means that 57% are from other parts of Virginia -- Hampton Roads (14.5%), Southwestern Virginia (10.5%), the Charlottesville area (7.5%), the Richmond area (7%), and Shenandoah (3.5%).  Another 7.5% live somewhere else.   
According to the U.S. Census bureau, about 32% of the state's population lives in Northern Virginia, so RK readership is weighted somewhat disproportionately (43%) in that direction. The Hampton Roads area has about 22% of the state's population, compared to 14.5% of RK readership. The Richmond area has about 16% of the state's population, but only 7% of RK readership. The Charlottesville area has about 2% of the state's population, compared to 7.5% of RK's readership. Southwestern Virginia has a population of about 354,000 (5% of the state) and 10.5% of RK readership according to the poll. The Roanoke metropolitan area plus Blacksburg and Lynchburg has about 5% of the state's population and about 6.5% of RK readership.
Please keep in mind that all of these are VERY rough comparisons, as it's difficult to find population statistics for different regions of Virginia, defined consistently.  Still, I think this poll probably provides a rough indication as to where RK readership is coming from.  What do you think?  Thanks.