How to check key size of RSA key created using aspnet_regiis?

I have created a customer RSA key container (for encrypting connection string in web.config) using the following command:
aspnet_regiis -pc "TestKeys" -size 2048 -exp
I then exported the key to an xml file and used it to initialise an instance of RSACryptoServiceProvider so that I could check the key size was definitely 2048. However, using the code below, the key size is displayed as 1024.
using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
{
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