Using Rijndael (as AES Algorithm) For Encrypting - Symmetric Key

Im using Rijndael (as AES algorithm) for encrypting. I encrypt the values (objects properties) and serialize the object to xml an dsend the xml to the receiver via a web service. I want to pass along the encrypted symmetric key that I used to encrypt the data. But what key should I pass along?

My decryption algorithm looks like this (vb.net):

CODE:

If I want to decrypt the encrypted string I have to use both key and IV, but I think I have to pass along only a key value. Do I have to do this another way or what should I pass along? My specification says that the values have to be encrypted using AES and a 128 bits key.