I am making my first red wine (RJ Spagnols Tempranillo) and was told that I should add 1 teaspoon of grape tannin to the kit (not included) to make the red more drinkable. Is this true?
With kit wines you should always follow the instructions. The kits are designed to give you a quality wine without any tweaking. Not saying that no one does tweak kits, but I would just follow the directions, it should have plenty of tannin already.
I would agree with Steve and the kit makers do a very good job at making sure the tannin level is correct for the style. Once you make this kit and if it doesn't have enough tannin for you could always add some on the next one.