By Lenn Thompson, Executive Editor I was first introduced to the Rkatsiteli grape when I tried the 2006 vintage bottling from Dr. Konstantin Frank Vinifera Wine Cellars. I was quickly hooked by the aromatic white that can be described as riesling-meets-gewruztraminer-meets-sauvignon blanc in its aromas and flavors with a beam of beautiful natural acidity. Since then, Dr. Frank’s Rkatsiteli has been a bit up and down for me — always drinkable, but sometimes without the verve and length of that first taste. Dr. Konstantin Frank Vinifera Wine Cellars 2009 Rkatsiteli ($15) is lemony on the nose with notes of citrus…