Profit Center Determination Rule

Hi SD/FI Experts,

Good Day!

Previous consultant do some changes in User Exit? (apologies for being not that knowledgeable for now in User Exit due to still leaning as Newbie) and sent it to our ABAP.

Now the ABAP give an advise to do the testing. I need to test if the changes to User Exit was successful.
I was thinking to create a sales order to test the changes but im having trouble on how am I gonna set the Sold-to Party as Profit Center Determination.
I only try to set the profit ceter thru material. But i'm not sure what to do to set the Profit Center Determination Rule thru Sold-to Party.

Hope you can help me.

Thank you very much in advanced