WeAuction offers a solution
For both the auction during CSI Ommen on Saturday 3 August, and the regular auctions in Ermelo on 17 and 18 September, it is possible to use WeAuction's online bidding system. The process of online bidding starts with creating an account via this link, something that is useful to do well in advance of the auction. It can take some time until the account has been verified by Foal Auction Prinsjesdag, and only then can you log in.
You can log in to the special bidding page from two hours before the auction, and after unlocking the bid button, you can bid live from anywhere in the world at the exact time of the auction. When a bidder has made the highest bid via the online bidding system, this will be confirmed in writing and the organization will contact you further after the auction.