Overhead vs direct cost of sale/service

Could one of the accountants please help me here.
I am a fitness practitioner and specialise in use of a particular machine for therapy and most my treatments are using this machine only. Due to the high cost of this machine I hire/rent it from the manufacturer and use it per patient (machine stays at the patient’s home during their period of treatment which could be upto several weeks. I charge patients a one off/fixed fee also taking into account the cost of the machine hire which takes up 60% of what I charge the patient.
My question is this - is the machine hire cost an overhead (equipment hire category in quickfile) or is it a direct cost and should be logged under cost of sales/service. I feel its a direct cost of providing the service.
Please advice.

that will be direct cost of providing the service

Thank you. I have logged them under “general purchase” so that they come under cost of sales/service. Hope I have done it right. If not please advice. Thanks again.