I do not recommend adding vinegar to bone broth. People love adding it because they read or heard somewhere that they should, but you don't need it. The idea is that it draws out more calcium from the bones. I believe everything should be in its correct and natural ratios for consumption. High pressure cooking for a couple hours is more than enough time to get plenty of calcium into the broth. It should also be considered that too much calcium in the diet can be an issue too. Aside from the calcium issue, the vinegar may add a slight flavor to your broth that you may not appreciate.