You follow these — you would never say them
de Peter, d Anna — the article before a name
The rule
First names almost always take an article: de Peter, d Anna, em Luca (to Luca). It is the normal, neutral form.
Das isch d Anna.
Das ist Anna.
Häsch de Peter gsee?
Hast du Peter gesehen?
Ich säg s em Luca.
Ich sage es Luca.
Where it catches you
In northern Germany «die Anna» sounds sloppy or dismissive. Not here — if anything, leaving the article out is what stands out.