将带有私钥的签名哈希的字节数组写入pdf文件的问题

Question

我像这样使用私钥对哈希进行签名

var signature = privateKey.SignHash(hash, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);

签名后，我想在签名的pdf文件上展示它。我尝试了几种方法但不起作用，有人可以帮助我吗？

这里是我的来源：

byte[] buff2 = File.ReadAllBytes(path);

        //byte to SHA256
        var hashAlgorithm = new SHA256Managed();
        var hash = hashAlgorithm.ComputeHash(buff2);

        // Load the P12 file containing the private key
        var cert = new X509Certificate2(Server.MapPath("~/bin/Agony-686-V1.p12"), "11111111");

        // Create an RSACryptoServiceProvider object from the private key in the certificate
        var privateKey = cert.GetRSAPrivateKey();

        var publicKey = cert.GetRSAPublicKey();
            
        // Sign the hash using the private key
        var signature = privateKey.SignHash(hash, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);

        //Do somthing to show a signed pdf file....