I was following the sizes listed here, and I've been creating the artboards with the sizes in points, but should I be creating them with the size for rendered pixels instead? Furthermore, I believe Sketch use points but correct me if I'm wrong.
As the page you linked to says, the point units are an abstract system for determining coordinates; they don't directly correspond to pixels on a screen but give a convenient coordinate space across devices; so you can have an icon that is always 40 × 40 pt even though it is rendered at different pixel sizes on different devices.
If you're creating raster images (i.e. made of pixels at a specific size) then you want to make your images at the actual pixel size of the screen. Namely;
- 320 × 480 pixels for original iPhones
- 640 × 960 pixels for iPhone 4/4S
- 640 × 1136 pixels for iPhone 5/5S
- 750 × 1334 pixels for iPhone 6/6S/7
- 1080 × 1920 pixels for iPhone 6/6S/7 Plus
The reason Sketch would (I assume, I don't actually use Sketch) use points is because it works with vectors. If you're working exclusively with vectors then all that really matters is the proportions of the image; so you can work in points (or any other size/unit in the correct proportions; points are just convenient) to create assets to be used across multiple devices and output at the correct pixel sizes when needs be.
Make them FullHD, 1080x1920 in pixels. Forget the pt unit in this case.
1136 x 640. this is the standard size of iphone and if you want to know exactly Capture the screen shot and bring it in photoshop there is the accurate size.