Hi Jason.
The request is as follows
Request method: POST
Request URL: https://xxx.myshopify.com/admin/api/2019-10/customers/{customerId}/metafields.json
Request header: { “X-Shopify-Access-Token”: “shpat_xxx” }
Request body: { “metafield”: { “namespace”: “joolen”, “key”:“points”, “value”:0, “value_type”: “integer” } }
Regards.