RSA is causing me headaches

Situation

I want to encrypt/decrypt byte[] data using RSA in my C# porject. I use OpenSSL.Crypto

this is my code

byte[] msg = System.Text.Encoding.ASCII.GetBytes("text to encrypt");

OpenSSL.Crypto.RSA rsa = new OpenSSL.Crypto.RSA();


byte[]result = rsa.PrivateEncrypt(msg, OpenSSL.Crypto.RSA.Padding.None);

Console.WriteLine(Convert.ToBase64String(result));

Question

1/ does my code look fine ? because i got an AccessViolationException. Here is the message "Attempted to read or write protected memory. This is often an indication that other memory is corrupt."

2/ how can i set/get public/private keys ?