Credit card

Learning center :-) Search for "privately paid" or something similar, and you will find an article.

Just use the document to record the expense. How it was paid (e.g. via private credit card) makes no difference for a sole proprietor. The document is all that matters.

You can also find a 'course' in the learning center. It states a section on private payments, which is also interesting.

You can transfer the money, but it makes no difference. Financial transactions (usually) have no impact on your accounts. As indeed stated in the article referred to by SL.

I did read it all in detail yesterday, thank you for your responses!