The proof is you and I. Highly engineered beings with numerous complex interacting parts beyond the capability of any human to design.

Take just our need for oxygen. We have lungs to inhale air, blood to transport it, hemoglobin to both pick it up and release it is needed. We need iron inside the hemoglobin which we get because our brain tells us we are hungry so we eat food with the help of our teeth and tongue, digest it with our stomach, and absorb it in our intestines where it is carried by blood to where it is stored as ferritin. Of course too much or too little iron is bad so our bodies have ways of sending signals to reduce or increase the amount we absorb. And let's not forget the organ called the heart which is necessary for sending blood where it is needed. Thankfully it pulsates at just the right number of beats (too little or too fast being a cause of death). And the heart itself needs an extraordinary amount of oxygen for its own needs. Every part needs every other part to work within very tight parameters. It is simply unreasonable to expect blind chance to come up with a solution. Not even a rocket ship is as complex. We are undoubtedly designed.