Create a JWT singed with RSA private key in .net core

The following example is a snippet of a C# code that generates an RSA private key out of a .pem file and uses it to sign a JWT. The privateKey variable, stores the contents of the .pem file minus the "-----BEGIN RSA PRIVATE KEY----" and "-----END RSA PRIVATE KEY-----" lines.

 
string privateKey = @"
MIIEpAIBAA
  ...
y53DdfYA==";
byte[] RSAprivateKey = Convert.FromBase64String(privateKey);
RSA rsa = RSA.Create();
rsa.ImportRSAPrivateKey(RSAprivateKey, out _);
var jwt = tokenHandler.CreateEncodedJwt(
   issuer: "...",
   audience: ...,
   ...
   signingCredentials: new SigningCredentials(
     key: new RsaSecurityKey(rsa),
     algorithm: SecurityAlgorithms.RsaSha256)
);