is there a suggested frequency used for hf radio and reticulum?
Yessir. Any packet radio modem that provides a standard KISS interface over USB, serial or TCP can be used with Reticulum. This includes virtual software modems such as FreeDV TNC and Dire Wolf.
https://m.youtube.com/watch?v=blwNVumLujc&pp=ygURUmV0aWN1b3VtIG92ZXIgaGY%3D
Discussion
HF is a range but common frequencies are 10m, 20m. nostr:nprofile1qqszw48usckkhs9hcwt3q3np9k2z2c73s8qc0gu3uxqw66cqlq88ukcpzemhxue69uhkummnw3ex2mrfw3jhxtn0wfnj7kacsqn would be more knowledgeable.
Reticulum is sort of agnostic. I knownit works over LoRa via the RNode firmware but i'm unaware of other implementations.