Sorry, for my question, but this situation hard to understand. If I get SOV on Metamask ETH adreess, I will not be able to send it or another ETH address (not Meatamsk)? Unfortunatelly, I'm not good known about RSK mainnet...
You must make sure that you change from ETH mainnet to RSK mainnet within metamask, to be able to interface with SOV.
There are other wallets support RSK mainnet like Nifty, Mathwallet and Liquality - but Metamask is the most commonly known.
One thing to watch with Metamask is always check your transaction fees - they don't always autofill