How can I combine two .csv files using c#?

StreamReader rdr = new StreamReader("<pathtoyourmasterfile>");
string master = rdr.ReadToEnd();
rdr.Close();

rdr = new StreamReader("<pathtoyournewdatafile>");
string newdata = rdr.ReadToEnd();
rdr.Close();
rdr.Dispose();

//The New Data .csv file will have headers. Need to remove those.
newdata = newdata.Substring(newdata.IndexOf('\n') + 1);

StreamWriter wtr = new StreamWriter("<pathtoyourmasterfile>");
wtr.Write(master + "\r\n" /*That \r\n may or may not be necessary*/ + newdata);
wtr.Close();
wtr.Dispose();

public static void AppendCsvFiles(string baseFile, string[] newFiles, string outFile)
{
    var baseLines = File.ReadAllLines(baseFile).ToList();
    Log.Info($"Total Lines in Base File: {baseLines.Count}");
    foreach (var f in newFiles)
    {
        var newLines = File.ReadAllLines(f);
        baseLines.AddRange(newLines.Skip(1));
        Log.Info($"Total Lines in {f}: {newLines.Length}");
    }
    Log.Info($"Total Lines in Combined File: {baseLines.Count}");
    File.WriteAllLines(outFile, baseLines);
}