I was hoping to hear right back from you with some additional information, but I will send my answer now, and if you have any additional questions, just click reply.
Introducing a new kitten to a resident cat can be a challenge. It also depends on the personalities of the two cats. Your older cat was used to being 'king of the castle' and here comes this 'intruder' who is invading his territory and also, taking up some of your time, which you could be spending with him. This is a very natural and instinctive reaction, but they will work it out, with your help.
As you know, cats can be very territorial and he may not like sharing his space with the new kitten; however, if you are able to use a good new process, this will help. Cats love routine and any minor changes can make them stressed. The first thing I’d recommend, is a ‘scent transfer.’ Take a slightly dampened cloth or paper towel and pet your cat with it, then pet the kitten, then, vice versa. Do this frequently throughout the day. You can also take an old t-shirt of yours and pet them both, so your comforting and familiar scent is carried on their fur all the time. Giving rewards (healthy treats) to both of them (especially your older boy) for good behavior, is also a good idea, as cats associate eating with a pleasurable experience, which will they will then associate with each other. It's very important to take things slowly and follow the most appropriate method for new introductions. You can see more detailed information at this link:
You can use the following products to help your older cat with stress:
Don’t use the Rescue Remedy and Composure chews simultaneously; choose only one. However, both can be used with the Feliway diffuser. There is also a collar that contains calming pheromones similar to Feliway; one is made by Sentry and the other, by Meridian, called Nurturecalm:
Try to interest your cats in interactive toys and others, so they're kept occupied and your older cat will associate enjoyable 'playtimes' with the new kitten.
When you get the new toys, divide them into several groups. Change out the groups every few days, and they will feel like they're getting 'new' toys, which will intrigue them, more.
You should have or can get, a tall kitty condo or cat tree with different levels, shelves, and 'hidey holes' for playing, sleeping and scratching (these are covered with carpet). Cats like to be up high, so if your older cat can be on top of the kitty condo, he will feel this is his domain and will feel safer. He will also enjoy a foraging toy, which fulfills the natural instincts of stalking and hunting prey. (more on that, below)
Interactive toys you can play with them, are laser pointers and feather dancers or fishing pole toys. There are even 'automatic' laser toys which you can set on a timer. Another thing he will like, is a dvd with 'critters' of different types playing and doing other activities. I will list information for these types of toys in the links below: