When you want to provide evidence or support for a statement, the phrase "in proof of which" can come in handy. However, there are several other phrases that you can use as synonyms in such cases, such as "as evidence," "to demonstrate," "for example," "as indicated by," and "as illustrated by." These phrases help you convey your point more effectively, which helps you establish credibility and persuade your audience. Whether you are writing an academic paper, a business report, or a persuasive speech, using synonyms for "in proof of which" can help you communicate your ideas better and leave a lasting impression on your audience.