(I learned this way from Ewan and improved it through Kira's advice so basically credit to them 
)
1 → Finish your signature.
2 → Create a New Layer (Ctrl+Alt+Shift+N) and apply the image (Ctrl+Alt+Shift+E)
3 → Select the Rounded Rectangle Tool and change the settings to look like this (you can change the radius to whatever you want but I suggest nothing under 30px):
4 → Select an area that looks like this:
5 → Right click within the black area and select Make Selection. Go to the Edit menu at the top left, and select Copy, or Copy Merged if Copy does not appear. Create a new canvas the size of your original signature. Paste (Ctrl+V).
6 → Go back to the first canvas and undo the Rectangle Tool and Selection. Easier to do if you have the History window up where you can just click back to Stamp Visible.
7 → Do the same as step 4 but on the opposite side. Follow through step 5.
8 → You should see a faint grey line in the lower left corner, click Layer 1 and then erase around the left and right sides near here:
Click layer 2 and erase the upper right corner so you can see the rounded edge.
Merge Layer 1 and Layer 2.
9 → Go back to the first canvas and move the applied image onto this new canvas. Place it and then right click that layer and click Create Clipping Mask.
You are done.
)1 → Finish your signature.
2 → Create a New Layer (Ctrl+Alt+Shift+N) and apply the image (Ctrl+Alt+Shift+E)
3 → Select the Rounded Rectangle Tool and change the settings to look like this (you can change the radius to whatever you want but I suggest nothing under 30px):
4 → Select an area that looks like this:
5 → Right click within the black area and select Make Selection. Go to the Edit menu at the top left, and select Copy, or Copy Merged if Copy does not appear. Create a new canvas the size of your original signature. Paste (Ctrl+V).
6 → Go back to the first canvas and undo the Rectangle Tool and Selection. Easier to do if you have the History window up where you can just click back to Stamp Visible.
7 → Do the same as step 4 but on the opposite side. Follow through step 5.
8 → You should see a faint grey line in the lower left corner, click Layer 1 and then erase around the left and right sides near here:
Click layer 2 and erase the upper right corner so you can see the rounded edge.
Merge Layer 1 and Layer 2.
9 → Go back to the first canvas and move the applied image onto this new canvas. Place it and then right click that layer and click Create Clipping Mask.
You are done.
Mhm aha it looks so great.
I love you! I will try this when I get home tonight!