1. create the source distribution:
   
   ./configure --enable-dist

2. create extra subdirectories:
  
   cd rpm && mkdir SRPMS BUILD SOURCES RPM

3. copy the resulting .tar.gz file into the SOURCES directory:

   mv smallbasic-0.10.8.tar.gz rpm/SOURCES

4. invoke rpmbuild:

   rpmbuild -v -bb --clean SPECS/opensuse.spec