Question

if 2 atoms combined their 4f orbitals, what type of orbitals should form?

Answer 1

I looked for, but could not find, anything on Google that gave an answer to your question. I did find this site that gives some info on how to set up MO bonds. Perhaps it will help you get started.
https://www.chem.fsu.edu/chemlab/chm1046course/motheory.html