Cosmos StoredProcedure

using System;
using System.Net.Http;
using System.Threading.Tasks;

namespace CosmosCreateSproc
{
    class Program
    {
        static async Task Main(string[] args)
        {
            HttpClient client = new HttpClient();

            string key = "*******************..........";
            string dte = DateTime.UtcNow.ToString("R");
            string cosmos_acct = "cosmos-***********";
            string cosmos_db = "ToDoList";
            string cosmos_container = $"Items";
            string procName = "TESTSPROC_DELETE";

            string procDef = "function() {\r\n var context = getContext();\r\nvar response = context.getResponse();\r\nresponse.setBody(%22Hello, World%22);\r\n}";

            client.BaseAddress = new Uri($"https://{cosmos_acct}.documents.azure.com");
            client.DefaultRequestHeaders.Add("x-ms-version", "2018-12-31");
            client.DefaultRequestHeaders.Add("Accept", "application/json");
            client.DefaultRequestHeaders.Add("x-ms-date", dte);

            string authTkn = GenerateAuthToken("POST", "sprocs", $"dbs/{cosmos_db}/colls/{cosmos_container}", dte, key, "master", "1.0");
            await CreateSproc(client, authTkn, procName, procDef, cosmos_db, cosmos_container);

            client.Dispose();

            Console.ReadKey();
        }

        static async Task CreateSproc(HttpClient client, string auth, string sprocname, string sprocDef, string database, string container)
        {
            string payload = $"{{ \"body\": \"{sprocDef}\", \"id\": \"{sprocname}\" }}";

            using (var msg = new HttpRequestMessage(HttpMethod.Post, $"dbs/{database}/colls/{container}/sprocs"))
            {
                StringContent sc = new StringContent(payload);
                msg.Content = sc;
                msg.Headers.Add("authorization", auth);
                using (var response = await client.SendAsync(msg))
                {
                    string responseMsg = await response.Content.ReadAsStringAsync();
                    Console.WriteLine(responseMsg);
                    response.EnsureSuccessStatusCode();
                }
            }
        }

        // Creates an Auth token for Cosmos REST API per spec.
        static string GenerateAuthToken(string verb, string resourceType, string resourceId, string date, string key, string keyType, string tokenVersion)
        {
            var hmacSha256 = new System.Security.Cryptography.HMACSHA256 { Key = Convert.FromBase64String(key) };

            verb = verb ?? "";
            resourceType = resourceType ?? "";
            resourceId = resourceId ?? "";

            string payLoad = string.Format(System.Globalization.CultureInfo.InvariantCulture, "{0}\n{1}\n{2}\n{3}\n{4}\n",
                    verb.ToLowerInvariant(),
                    resourceType.ToLowerInvariant(),
                    resourceId,
                    date.ToLowerInvariant(),
                    ""
            );

            byte[] hashPayLoad = hmacSha256.ComputeHash(System.Text.Encoding.UTF8.GetBytes(payLoad));

            string signature = Convert.ToBase64String(hashPayLoad);

            return System.Net.WebUtility.UrlEncode(String.Format(System.Globalization.CultureInfo.InvariantCulture, "type={0}&ver={1}&sig={2}",
                keyType,
                tokenVersion,
                signature));
        }
    }
}

Very good, thank you for all your help.