A method performed by a transmitting device is provided. The method includes at least one of: receiving an indication of an aggregation of N reference signal (RS) resources, the N RS resources each comprising a number of RS ports P1 and being selected from a group of M RS resources, N being at least 1, and M being at least 2, Determining a number of RS ports, P2, as a number of RS ports in the aggregation of RS resources, according to the indication of the aggregation of N RS resources, where P2 is greater than or equal to P1, receiving an indication of a precoder to be applied to a physical channel, optionally, the precoder being for use in a P2 port transmission of the physical channel; and transmitting the physical channel using the indicated precoder. Other methods, apparatuses, computer programs are provided.