hektiksnip
couple of things, but main thing is:
Make the VTF 2048x2048. The dimensions need to be a power of 2. examples 4x4, 32x32, 64x64 (64x32 would also work afaik)
The dimensions in the text file can be whatever, but I recommend just centering the 1920x1080 image on a 2048x2048 canvas and making it a VTF, then using 2048 for width and height in the text file as well. Keeps things simple
As for your VTF flags I recommend also selecting "No Minimum Mipmap" underneath "No Level of Detail". I don't actually remember what it affects but I've always had it selected so no harm done if you do
I also recommend the first flag "Point Sample" for this particular crosshair since this will remove a tiny bit of remaining blur. I recommend using point sample for crosshairs like crosses and such, though it is not required at all for them to work nor is the tiny blur a big deal. Most people won't even notice the difference