Polkadot and Kusama are completely separate networks from Ethereum or BSC, which is why there are no contract addresses like you may be used to with ERC20 and BSC20 tokens. 

Therefore DOT and KSM are currently not available on Uniswap, MetaMask, Pancakeswap or other projects of the Ethereum or BSC ecosystems. 

There are "wrapped" or "pegged" tokens on both networks for both DOT and KSM, but these are not native tokens. They simply represent DOT or KSM, but they can't be sent to native Polkadot or Kusama accounts.

IMPORTANT: The contract address shown on CoinMarketCap, which you can add as an asset in Metamask, is for the DOT-pegged "wrapped" BEP20 token running on BSC, as mentioned in the banner on top. Do not confuse this with Polkadot's native DOT token.

Be aware that there are also scam tokens on both networks! If you need to use these wrapped tokens, verify first that you are interacting with the legitimate contract, because anyone can create a smart contract and name it however they want.