Are you just asking whether you can put smaller wheels on your Sport? If so, the answer is yes. I saw several RAV4 Sports this winter running winter tires on 17" steelies from a base RAV4. Your Toyota dealer, or tire dealer, may already sell packages of that sort. The RAV4 in the US is also sold with 16" steelies, but 17" is the smallest stock size in Canada.
If you want to go with a generic, non-Toyota wheel, your tire dealer should be able to help determine whether or not a particular one is a good fit for the RAV4.