...
curl -X POST --header "Accept: application/fhir+json" --header "Content-Type: application/fhir+json" --header "Authorization: Bearer aaaaa-bbbbb" --header "X-Org-Public-Id: 235a397b-1ae8-4755-9c77-1a0e2fbc5314" "https://sandbox.patientsknowbest.com/fhir/Questionnaire/bd17e556-20e3-4f01-8078-30e5f675b0f2/$send-questionnaire-request" --data "{\"resourceType\":\"Parameters\",\"parameter\":[{\"name\":\"target\", \"valueReference\":{ \"identifier\":{ \"system\":\"https://fhir.nhs.uk/Id/nhs-number\\", \"value\":\"5193233945\"}}},{\"name\":\"requestor\",\"valueReference\":{\"reference\":\"Practitioner/bdaa24d0-3cd5-469c-aa69-db676fa31bbe\"}}]}
...