Relays for Alpeh P 1.7

I'm studying the PCB of Aleph P 1.7.
For the volume control we know that a microcontroler is overkill, but it's not the problem here.
The Principe of the relays N/A converter looks good, but can you give me some precise reference on the relays can we us in it ? For find the pattern in order to put on my PCB.