I would like to add a service-endpoint to my Kilt DID, using the Javascript SDK.

I have created a full DID and am trying to add the service-endpoint like so:

  const extrinsic = api.createType('Extrinsic', { id: `#${id}`, type: [type], serviceEndpoint: [url] });

  const authorizedTx = await Did.authorizeTx(
      didUri,
      extrinsic,
      signRequest(didUri, didAuth),
      submitterAccount.address
  );

the extrinsic is not correct as I get an error

SDKError: No key relationship found for extrinsic

I was not able to find this specific actin in the Kilt documentation, so I'm asking here.