How to call SQLScript Proceduer in SAP River

Hi experts,

I want to use procedure in my RDL file, so i write the code using the following way:

action callExternalProc() : Integer {

let x: Integer = sap.hana.catalog.EXTERNAL_SCHEMA.PROC1(5);

return x;

}

but there is an error:

Cannot resolve symbol sap.hana.catalog.EXTERNAL_SCHEMA.PROC1

No such action (PROC1)

could you give me some suggestions?

thanks