Atomic Ethereum Wallet supports ANY ERC20 tokens. If you haven't found your token in the list just click on the "Add token" button.
To add your token just paste your token's contract address.
All other data (Full name, Short Name and Decimals of precision) will be updated automatically.
To find your token Contact Address:
Go to https://etherscan.io and make a search for your token name.
Copy Contract Address and paste it in Atomic Wallet.
All other information will be filled automatically. Now you have your Custom Token in Atomic Wallet.
The token will be attached to your Ethereum address. You can now send, store or receive this token in Atomic Wallet.
Please don't forget that all ERC20 tokens are based on Ethereum. To manage such assets you will need to have at least a small amount of ETH in your wallet.