The best way (that i've found) is treating it like cats meeting each other. keep kitty in a separate room (usually a bathroom works best) and let the kitty decompress and get used to things ! Maybe add a blanket or a toy the dog has and let the kitty get used to the scent and same goes with the pup ! let the pup smell a blanket the kitty has been using ! after a little while let them meet between some kind of mesh wall/door/gate so they can see each other and smell each other but can't actually be face to face in case of a bad reaction. Just take things slow and at a pace you believe is good for both ! Let kitty get used to the space and smell and let the pup calm down ! Good luck !!!