How can I make sure that the knob send matches the other knobs in my house?

For Reliabilt locksets you have to pay a professional to have the locks all keyed the same. Lowe's can do it, you just have to pay them to do it.

This unit is part of the keyed alike program for in store purchase. The online items do NOT participate in the keyed alike program. If you purchase this item from online, you will need to see a Lowe's hardware associate and have them rekey your purchase to match the other units on your home. They may charge a nominal fee to do so. The key alike number is not tracked by the company and is not the key number itself.

The best way to get the same style of lock that you have, is to go to your local Lowe's, and purchase the lock there. The Hardware Associate should be able to re-key the lock for you so that the same key will work. There is no guarantee that if you ordered it on line that you would get the same key and or style.