Lets suppose that u want to upload the verdana font.
goto se73 transaction->click the system font radio button->
now click the last button true->type font installrein->u will be asked to enter the family name->give ZVERDANA.
Now u need to upload 4 files
while uploading the normal verdana do not check any boxes
execute the program and u will be prompted for the file
u can get it from c\windows\fonts
type in the file name which will be verdana.ttf
now the normal font is uploaded
for uploading bold, check the bold check box and upload verdanab.ttf
same is for italic and bold italic
Each time u try to add a new file to same name ZVERDANA it will prompt u. Click the Y button to include the 4 files under the same name ZVERDANA
I hope you understand.you can do this way.
Use the progarm RSTXSF01 to instal new font
See the link for more info
Please reward points if it helps