first tranfer all tokens and eth to other wallet than enter your private key.
this is the safiest way also never use that wallet again
Oh, that appears very serious. Here's their explanation, maybe it'll throw more light into the matter:
"Please Note: Your private key is required to verify that you are the owner of the wallet you specify. It also allows our smart contract to calculate the number of tokens to airdrop. You must have a balance of either ETH or KIN tokens in order for the smart contract to execute the airdrop.
The form is fully encrypted and your private key is neither stored or visible to anyone. The tokens will be deposited to your account, normally within 10 minutes, but is dependent on the speed of the Ethereum network, so please be patient"