About OIDC's ID Token Verification

API
3

Thank you.
It was helpful and I’m almost ready to complete the verification.
I would like to know how I can get the Certificate for RS256.

var json = JwtBuilder.Create()
                     .WithAlgorithm(new RS256Algorithm(certificate)) // asymmetric
                     .MustVerifySignature()
                     .Decode(token);                    
Console.WriteLine(json);

Or I want to know how to generate a public key.
https://id.twitch.tv/oauth2/keys
How can I generate a public key from this?