As we have already informed you that Google is going to rollout Android 4.4 Kitkat update to Nexus 7 and Nexus 10 update. Now, Some users have received it and some are receiving.
If you haven’t received the Android 4.4 Kitkat update – build KRT16O on the 2013 Nexus 7 than you can sideload it on your device from the link mentioned in the source. Link is directly from the Google’s official repository.
Before moving ahead you should know how to sideload it by adb sideload command through adb and the Android SDK.
Source: Download Link