Train from Schiphol to Antwerp?

I would take the IC service, direct or with a change in Rotterdam. Those are flexible tickets, which you can use on any IC train. If all goes smoothly, you can take an earlier train. If not, a later one. Tickets for the Thalys always include a reservation, which binds you to a specific departure time. You can change those full price tickets, but that will take time which you possibly won't have.
The connection in Rotterdam shouldn't be a problem. The IC DIrect from Schiphol arrives at track 4; the IC to Antwerpen (with Brussels as final destination) leaves from track 3. They're opposite on the same platform.
Buy those tickets in advance, saving you precious time at the ticket window at Schiphol. (Dear NS charges an extra EUR 2,50 for payment by credit card. They still don't realise there are also foreign customers.)

I completely agree with Tomfromleiden. Buy your IC tickets in advance. If you're lucky, you'll make the 10:08 departure. Schiphol is an easy airport to navigate--as long as your flight is on time.

Thanks for your responses! Do the IC trains (IC Direct and IC Brussels) have storage for bags? My roller bag is the maximum size one can bring for airline carry-on.

Note for the future that Thalys is much cheaper months in advance, and flying to BRU the most efficient. Besides the train, there is an hourly direct bus from BRU to the Antwerp rail station.

Just keep your carry-on right close with you . I've been on the IC train from Schiphol to Antwerp in the morning and the train was not crowded at all so you are not imposing on fellow travelers . There are however folks who like to hop on and at departure time grab your carry-on , laptop , whatever is easy pickings . That's why you keep your roller bag close to you and not too close to the aisle . As tonfromleiden pointed out , the transfer in Rotterdam is a piece of cake , turn around and there's the train to Antwerp .Have a great river cruise tour !

Not to hijack thread, but we just booked roundtrip next spring between Philly and Amsterdam, and will immediately leave on arrival for Ghent as our first stop (and, no, airfare was double involving Brussels). My question is that I have some confusion regarding the train tickets, namely, whether we trust a timed Thalys, or go with the Dutch IC, who do we buy them from in advance? Thanks!

Larry, I do not know about any alternatives that might be cheaper, but I do know that NS sells these international tickets from https://www.nsinternational.nl/en . They sell tickets for the Thalys, Intercity Direct and Dutch/Belgian intercity trains. For the Thalys the time you select does matter; for the other trains only the date does.

I see there are some construction works around the border this summer, so it could be that some trains have to take another route. This will be displayed when you choose the tickets for any of the affected dates.

Stijn - Thank you! Was not the matter of least expensive, was simply a matter of where to do this. in the past I have had trouble figuring out the Dutch site. I think I may have been to other than the link you just gave me. I just did a trial on this for end of this year, and it seems fine. Only need to figure out how much time to allow, we land at 10:25 having gone through Passport control at the Frankfurt layover, and have carry-on only. Interesting on the trial that at roughly 11:30 I can do the direct 2 hour Thalys for 79 euro or the 3 hour IC for 45 euro, while at 12:30 I can do the 2 hour Thalys, arriving at the same time as the 11:30 ICE, for only 35 euro. Will figure out later the best way, given that Thalys is fixed to that train.