Thanks, John and David. Even with the example in hand, I find it hard to say how the signing has been done. The incision is deep into the material but the edges are smooth and fairly level with the parent material, as can be seen in the fourth photo of the original post. That outcome could be achieved by either cutting or pressing into the near molten material, perhaps with some further gentle working to smooth the surface without obliterating the incision. The only way that I'd be sure would be with second example for comparison, where the normal handwriting variations - even between two specimens by the same person - would indicate that the signature was cut freehand.
The only examples I can find online of a deeply incised signature on a Daum item are in quite different handwriting from what's on my little bowl, including different combinations of upper and lower case letters. But they are quite different objects, so they may also differ in time period and glassmaker.
Trevor