This creature does not need to be knocked out, it is a passive tame which means that you have to passively feed it by hand. This can be done by putting the food or kibble in your last hot-bar slot and pressing "E" (or "Y" on Xbox One) to feed it. Make sure to keep track of when it needs to be fed or else taming efficiency will slowly go down. The type of food you choose can also affect efficiency with kibble giving the highest and other berries giving the lowest. However, kibble can be harder to get in early stages.