現時香港人有冇在碌卡時把簽名簽在碌卡機中呢?

In theory, yes - VeriFone, a credit card terminal manufacturer that provides touch-based (for signature) terminals have an office in Hong Kong.

In practice, no - merchants in Hong Kong, unlike those in the U.S., actually verify the signature on the receipt with the one on the back of the card. Also, the merchants have the credit cards in possession when the transactions are processed. This makes signing on the machine not practical.