ZOHO CRM : Insert Invoice using InsertRecords API

We are working on a WordPress plugin which will create the new entry inside invoice module in the ZOHO CRM when the order is processed using the API.

From the API Docs, it can be done using the insertRecords API.

URL:

https://crm.zoho.com/crm/private/xml/Invoices/insertRecords

Also, we need to pass the following parameters to insert the invoice:

https://www.zoho.com/crm/help/api/modules-fields.html#Invoices

We have confusion about the Lookup data type fields ( http://prntscr.com/hg72sj ).
Can we pass the Ids instead of the name in this lookup fields or provide a proper example for this kind of fields.

Also, If you can provide the same for the products as well that will be great.