This method initiates a new payment associated with merchant generated transaction to be finalised by the customer using bank/MNO digital channels. You are required to setup payrequest.success and payrequest.reversed webhook events. For payload explanations for both request and response, click here 
using OneKhusa.SDK; 
using OneKhusa.SDK.Models.Transactions.Collections; 

//code omitted for brevity 

OneKhusaResponse<RequestToPayResponse> response = await client 
    .Transactions 
    .Collections 
    .CreateRequestToPayAsync(new RequestToPayRequest 
    { 
        MerchantAccountNumber = 12345678, 
        ReferenceNumber = "OK0987654321", 
        TransactionAmount = 6500000.00M, 
        TransactionDescription = "Samsung 85inch TV purchase", 
        CapturedBy = "joe.doe@example.com" 
    }); 

if (response is { IsSuccess: true, Data: not null }) 
{ 
    Console.WriteLine($""" 
            MerchantAccountNumber: {response.Data.MerchantAccountNumber}; 
            TimedAccountNumber: {response.Data.TimedAccountNumber}; 
            ExpiryDate: {response.Data.ExpiryDate};  
            ExpiryInMinutes: {response.Data.ExpiryInMinutes} 
        """); 
    return; 
} 
//it means an error has occurred: RFC7807 compliant error object
Console.WriteLine($"""
        Type: {response.Error?.Type};
        Title: {response.Error?.Title};
        Detail: {response.Error?.Detail};
        ErrorCode: {response.Error?.ErrorCode};
        Status: {response.Error?.Status};
        Instance: {response.Error?.Instance};
        Errors: {string.Join(";", response.Error?.Errors ?? [])}
""");
Console.ReadLine();
Note: This method accepts custom idempotency key generated by your system. By default, if not specified, it will create one on your behalf.