How to use existing FM in Generic datasource

Hi All,

I have seen couple of doc regarding Generic datasource on FM called  RSAX_BIW_GET_DATA_SIMPLE using as templet to  create generic DS ,but I want to use this FM "RP_FILL_WAGE_TYPE_TABLE"  in generic datasource  to get  Basic salary( monthly ) and Personal Element. I guess I need to create Extract  Structure explicitly with required fields.

Please any inputs in this?

Thanks

Hari .