That foot is a No.
The box is the important piece of work so the foot needs to be as small as possible, just enough to lift it of the surface it rests on. The under curve of the lower part of the sphere needs to look like it is floating off that surface. Don't think you can achieve that from where you are now, maybe next time.
So if you are adding a foot, no more than 1/3rd the height of the sphere and about 1/3rd the diameter as well, it's all about proportion,.
As for the finial, stop turning them and looking to see if they look right, draw a circle (with prefered foot if necessary) and draw, draw until you see the one that is right. Truthfully, I'm not sure an ornate finial will work, think knob, something big enough to lift it. Give it a good shape but don't overwork it. Another option is a 'found' finial, a bit of antler, an interesting stone or strange bit of metal, anything as long as it is 'in proportion' to the overall height of the turning and does not overpower it.
Play, experiment, if nothing seems to work, put it to one side, eventually the right 'thing' will put itself in front of you in that 'ah-ha' moment.