It’s problematic when using a smaller screen device, like a Macbook, with an Artboard that has larger dimensions than Macbook’s screen dimensions. It then scales and fits the content of the Preview to that smaller screen, which is not desired when designing user interfaces.
The same thing could be replicated on a larger screen by simply dragging the Preview window smaller than the dimensions of Artboard it’s previewing. Setting it to “actual size” there would be also beneficial.
I used Preview in browser plugin before, but that doesn’t work in latest Sketch versions anymore.
The Preview window works with the Artboard Templates you define for your Artboards. This means that if you want to see your design at 100% scale, you can:
Assign an Artboard Template that is smaller than your current screen
This will make the Prototype window use that size, and then show the content at 100%.
One of the CoolThings you can do with our latest beta, is to create a Scrollable Prototype (in any direction) which might allow you to inspect any part of your design if you wish it so!
Note:Please, carefully read the disclaimer on the beta page before proceeding. As always, we recommend using these builds with copies of your Documents, just in case.
Create a new Artboard using any Template you want to use.
Insert a Shape that fills 100% of the Artboard (both width and height).
Convert it to an Scrollable Mask
Insert your design (it can also be a Symbol!) in the appropriate location.
While this would work, it means modifying every artboards everytime you want to visualize it. Or having to build you’re design in consequence with big scrollable groups.
Instead of just having a zoom options for the prototype player…
The prototype player as always been lacking zoom wise. It’s even better, although still not that great, on sketch.com.
you can do with our 
I was just playing around with the new Sketch version and noticed this: