Hi,
Yes it can use excel format as well as .txt also. Basically you need to right an ABAP Code using the above BAPI.
I would also suggest you to use LSMW - with Standard Batch/Direct Input Option.
Object - 0100 (Financial Document)
Program - RFBIBL00
Using an LSMW would not require any ABAP Coding or Program. Plus LSMW creation make it as an Header & Input File option.
Please explore above Program/LSMW.
Regards,
Jaymin R. Bhatt