Determining a Reference Customer 
You must know the (or a) reference customer before you can execute the
BAPI_CUSTOMER_CREATEFROMDATA BAPI. This BAPI is used in the following examples provided in the SAPforms documentation:The reference customers used in your company (and therefore the other sales data) are normally known. If this is not the case, you can determine the reference customers from the internal number ranges. You can only do so, however, if the reference customer was created with the internal number assignment function.
In other words, there are two ways of finding a suitable reference customer:
From a business perspective, it makes more sense to create a separate reference customer for the form application. To do so, use the transaction
V-09.Procedure
Determine the Internal Number Ranges
Determine the Reference Customer

It is important that the sales data and company code data have been maintained for this customer. You can maintain this data, if necessary, with the transaction
Create a Reference Customer
To create a reference customer start transaction
V-09.