Process jars in a water bath or steam canner for 15 minutes (all jar sizes); increase time as needed for your altitude.
[Optional] Per 1/4 litre (1/2 US pint) jar, 1/8th teaspoon liquid stevia. Per 1/2 litre (US pint), 1/4 teaspoon liquid stevia. Per 1 litre (US quart) jar, 1/2 teaspoon liquid stevia.
Start out with only a small amount of blanching water, just enough to cover the berries, because as you blanch the berries they will release juice and the amount of liquid will increase. That way, you end up with purer and less watered-down juice to use for packing the berries in.
The small 1/4 litre (1 cup / 1/2 US pint / 8 oz) jars are handy for baking; you may wish to can some of those at least unsweetened for maximum flexibility when you go to use them.