Inclusion Criteria:  Males and females aged 18 to 65 years are competent to consent to treatment have a Mini-International Neuropsychiatric Interview (MINI) confirmed diagnosis of DSM-5 criteria Obsessive Compulsive Disorder. have failed to achieve a clinical response to one adequate trial of serotonin reuptake inhibitor or cognitive behavioral therapy with an adequate trial of 2 months medication within the current episode, or been unable to tolerate antidepressant medications. have a score ≥ 20 on the YBOCS. have had no change in dose, or initiation of any psychotropic medication in the 8 weeks prior to randomization are able to adhere to the treatment schedule pass the TMS adult safety screening (TASS) questionnaire  Exclusion Criteria:  Allergy to cycloserine. have an alcohol or substance use disorder within the last 3 months have suicidal ideation (score of 4 ≥ on item 10 of MADRS) are at a significant risk of harm to themselves or others Current symptoms of psychosis History of psychosis are currently pregnant , breast feeding or plan to become pregnant have a lifetime Mini-International Neuropsychiatric Interview (MINI) diagnosis of other primary psychiatric diagnoses as assessed by a study investigator to be primary and causing greater impairment than Major Depressive Disorder. have failed a course of ECT in the current episode. Previous ECT treatment outside of the current episode does not influence inclusion. history of non-response to rTMS treatment. have any significant neurological disorder or insult including, but not limited to: any condition likely to be associated with increased intracranial pressure, space occupying brain lesion, any history of epilepsy, cerebral aneurysm, Parkinson's disease, Huntington's chorea, multiple sclerosis, significant head trauma with loss of consciousness for greater than or equal to 5 minutes have concomitant major unstable medical illness, cardiac pacemaker or implanted medication pump have an intracranial implant (e.g., aneurysm clips, shunts, stimulators, cochlear implants, or electrodes) or any other metal object within or near the head, excluding the mouth, that cannot be safely removed If participating in psychotherapy, must have been in stable treatment for at least 3 months prior to entry into the study, with no anticipation of change in the frequency of therapeutic sessions, or the therapeutic focus over the duration of the study are currently (or in the last 4 weeks) taking lorazepam or any other benzodiazepine due to the potential to limit rTMS efficacy