Last night, Google announced that we should start to see Android 4.4 updates for the Nexus 7 (2013) and Nexus 7 (2012) WiFi models, along with one for the Nexus 10. The update as build KRT16O for the 2013 Nexus 7 began pushing last night and is now available for sideloading should it not have popped up on your device yet. Below we have the official link directly from Google for the update file
In order to flash, you can use the “adb sideload” command through adb and the Android SDK (instructions). If you are stock with root and recovery, flashing the .zip file through recovery often times works.