When it's appropriate:
* Professional contexts where your credentials are relevant: A signature on a research paper, a medical report, or a letter from an academic might benefit from including both "Dr." and the degree to clearly establish your expertise and qualifications.
* Situations where ambiguity might arise: If your name is common, or if your field uses the title "Dr." for multiple degrees, including your degree clarifies which discipline you practice in (e.g., Dr. Jane Smith, PhD; Dr. John Doe, MD).
When it's less appropriate or might be considered excessive:
* Informal settings: A casual email or a handwritten note to a friend doesn't require this level of formality.
* Business contexts where it's unnecessary: A simple business letter might only require "Dr." or your full name. Including your degree might seem boastful or overly formal.
* Government forms: Forms often have designated spaces for titles and degrees, rendering the inclusion of both in the signature redundant.
In short: Use your best judgment. If including both "Dr." and your degree adds clarity and is relevant to the situation, it's fine. If it seems excessive or inappropriate for the context, it's better to err on the side of simplicity. Using only "Dr." is generally sufficient in most professional situations.