Another hello and welcome from me. I expect that the rescue will give you a supply of his usual food so maybe stick with that for a few days while he settles down. Like Tinyplanets, I don't tend to do the transition thing and my dogs have been fine but many companies suggest that you gradually change over to the new food.
Anyway, on the subject of choosing a food, at that age he should be able to have adult food. If you go to the main website home page you can put the dog's details in and it will give you plenty of suggestions. The better quality foods are not found on the supermarket shelves so if you can, locate a specialist pet store and have a wander round. Look for products with a named single meat/protein source (unless it is one with several types of meat and/or fish) and it needs to be first on the list of ingredients. Foods with more meat tend to have smaller amounts of carbohydrate/fillers so they are usually the best ones. Some people prefer grain free kibble and these days there are plenty of options for this type of food. Again, you can filter this out on the left hand side of the 'Foods' tab. Once you have selected a few foods that interest you, you can check them out in the directory of the site. There you will be given an appraisal of them so that you can narrow it down further. There is also a 'compare' tick box in the centre of the description box for each food and you might find that quite useful.
With kibble you don't need to add tinned meat because they are complete in themselves but some people do use a small amount of it as a topper to make the dry kibble more palatable. It may be best to concentrate on getting the kibble right before you add the tinned food so that you know what suits and what doesn't. Don't forget that you can also top the kibble with a little bit of mince or perhaps oily fish such as sardines, mackerel etc. Those sorts of things are nutritious. You can also pour a spot of warm water on it to bring out the aroma of the food - dogs enjoy smelly food.
Your new dog is a very active breed and he is quite young so choose the best food that you can afford. If you select one and want an opinion or advice, we will try to help. BTW congratulations on your new pal. I hope that you enjoy each other's company and have lots of fun together.