The best way to make your dog dry food softer is by pouring some warm water onto it. If you heat the water, the taste and aroma of the food will also increase. Older dogs often have difficulties recognizing smells and seeing things, and they will appreciate these enhanced features.
If your dog is picky, try softening their food with a few spoonsful of chicken broth. If your dog needs more kibble that contains more vitamins and calcium, give it some warm milk and mix it for a nice creamy texture. Try putting the kibble and milk mixture in the refrigerator a few hours ahead. This will let the food properly soften.