Hi, Cindi.
If your goal is only to support the methylmalonate pathway, the adenosyl B12 will do that by itself, though you will likely need to increase the dosage.
If your goal also includes lifting the partial methylation cycle block and restoring glutathione, which is necessary for recovery from ME/CFS, then yes, you will need to add folate. I would not recommend folic acid, though. Methylfolate is the form needed by the methylation cycle. Folinic acid in addition can be helpful for most PWMEs.
Best regards,
Rich