this link may help you

https://link.springer.com/article/10.1007/s12221-015-5468-6

It depends a bit on the capabilities of your SEM-instrument and as log as your sample is in a dry state proceudre is like investigation of any inorganic powder. For "normal" instruments, you just put some dust of your sample on the sample-holder with a fresh conductive adhesive pad glued on it. As MOFs usually are not electrical conductive you have furthermore to sputter the surface with gold before investigation.