RBAC Azure Reserved VM instance reader role assignment via REST

Is there a way to assign azure reader role to reserved VM instance?

I'm trying to use management.azure.com/roleassignments endpoint with no luck.

I need request uri like below

https://management.azure.com/{subSegment}/roleAssignments/{Guid.NewGuid()}?api-version=2015-07-01

to make role assignment for reserved vm.

I've been looking here

https://docs.microsoft.com/en-us/azure/role-based-access-control/role-assignments-rest

But this only describes subscription but I need to do this for reservation.

I have reservationOrderId and reservationId.

Cheers,

Adam