As a rule, most men's rain jackets are easy to store. Of course, it always depends on the model. If you are looking for a really robust rain jacket, the pack size is usually rather unimportant.
However, if you plan to wear the jacket only when it rains and otherwise store it in your backpack, you should pay attention to the packing size of the jacket. In this case, it is important that the pack size is small.
It is also advantageous if the rain jacket has a low weight. Since most rain jackets are rather thin, they are also easy to stow.